Physics+In+Action+Ch+2+JPrezant

http://prezantswiki.wikispaces.com/Physics+In+Action+Ch+2+JPrezant toc =Section 1=

The Science of Tennis http://www.odec.ca/projects/2005/wong5i0/public_html/ This article is about the sport tennis and the sciences of it. This article shows that tennis is not just hitting a ball, but there are "six major branches of science that can be covered: physiology, medicine, biomechanics, psychology, engineering, and technology." Physiology is necessary because it gives players needed information about their health in tough playing conditions. Medicine is important because it will help players with injuries, which are very common in tennis. Biomechanics is important because it allows players to use their energy in the most sufficient ways. Psychology is important because it allows players to not lose mental focus and always keeps their minds positive, even when they are losing. Engineering is important because it allows factories to make the best equipment possible for tennis. Technology is important because it allows officials to be more accurate when it comes to line calls, which lowers the amount of disputes on the court. Tennis is not just a sport with a ball and a racquet, there is much science included.

What Do You See I see a bunch of people playing soccer. One person ran very fast and kicked the ball, but kicked it over the goal. Another person just kicked a ball easily without running and the ball did not go very far. Also, a bug tries to push a ball but cannot make it move at all. A mouse tries to kick a ball but hurts itself trying to kick it. This picture clearly shows that if there is more force and momentum behind the ball, the ball will go farther.

What Do You Think 1. Once you attain a high speed you keep traveling fast because ice prevents friction, so you would keep on sliding at fast speeds. 2. It continues to roll because it is already in motion, but the ball will eventually come to a stop because the friction between the ball and the ground slows down the ball

**Investigate: Newton's First Law**

Hypothesis: The two vertical heights will be equal if the slopes are the same. If the slopes are slightly different then the vertical heights will also be slightly different. To be able to find the maximum height, it is necessary to know the initial height of the ball. 1c. 5.33m 1e. 5.33m 2a/2b. I think the skater’s maximum height will be 5.33m because the initial height always remains the same no matter what you change. 3a. My prediction was correct because the initial height did not change, the velocity of the skater did not change, making the maximum height 5.33m. 3b. The skater’s initial height will always be the maximum height reached because the initial height is where it changes direction and begins going downhill. 4a. I predict that the height will still be 5.33m. 4b. My prediction was correct. 5a. No because with a slope of 0, the skater will have nothing to force him to turn around since there is no area going uphill. In order to turn around, there must be a positive slope. 5b. The skater will keep on rolling until any force acts upon him that makes him come to a rest. 5c. As long as the skater has enough momentum, he will keep on rolling on the horizontal track. 5d. The skater kept on rolling until he fell off of the track. 6a. As the slope decreases, the length increases. 6b. The final vertical position on the opposite track will be equal to the initial height. 6c. The heights of both vertical heights are always equal. 6d. The skater would never stop unless a force some kind of force acted on the skater, decreasing his speed and bringing him to a stop.

Physics Talk -Galileo Galilei was an Italian physicist, mathematician, astronomer, and philosopher. -He was known as the father of modern science -He concluded that a ball will continue along a horizontal surface with constant speed along of straight line forever -He formed the law of inertia -inertia- the natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line. -inertia - property of matter that resists changes in motion -at first, Galileo thought that all moving objects would stop until he realized that objects do not stop by themselves. -Isaac Newton had an impact on science, government, and philosophy -he used Galileo’s law of inertia to develop Newton’s first law of motion, which stated in the absence of an unbalanced force, an object at rest remains at rest, and an object already in motion remains in motion with constant speed in a straight-line path. -he explained that an object’s mass is a measure of its inertia -he wrote the book Principia that he wrote his first law of motion in -a running start is important in many sports, such as javelin throwing -the javelin will continue at the same speed after being released -the speed of the javelin is a sum of the forward speeds in the hand, elbow, shoulder, and body - to show the speeds involved, the equation is: Vjavelin = Vhand + Velbow + Vshoulder + Vbody -velocity – speed in a given direction -acceleration = the change in speed at a certain time -acceleration occurs during starting, stopping, and changing direction -the object being thrown starts at your speed if you run with it and then throw it -speed is only speed and velocity is speed and direction -acceleration is change in speed, change in direction, or both Frames of Reference + Running Starts (increase distance +/or speed to give advantage) Frames of Reference "relative to" adding or subtracting velocities

Checking Up
6. It tells you the perspective you are looking at. It will look different if you are in compared to if you are out.
 * 1) Inertia is the natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line.
 * 2) Newton’s first law of motion stated in the absence of an unbalanced force, an object at rest remains at rest, and an object already in motion remains in motion with constant speed in a straight-line path.
 * 3) Any unbalanced force is needed to act on an object to stop it from moving at a constant speed.
 * 4) Friction slows down and eventually stops the motion of the ball.
 * 5) The greater the mass, the greater the inertia. So whichever one has the greater mass will have the greater inertia.

PTG #1-4, 10
1a. The ball will keep on rolling until a force acts on the ball. 1b. Newton's first law of motion states that an object will keep on moving unless a force acts on the object. 2. 20cm. It will reach the same height it started at. 3. It is not possible because of gravity. We cannot change gravity, and gravity will always make objects have friction with the ground, so it is not possible for something on earth to keep on rolling at a constant speed forever. 4. Since there is little to no friction between the puck and the ground because of the ice, the puck will keep on sliding for a very long time unless a force acts on it. If the puck hits a wall or goes into the goal, the puck's motion will be slowed down and will eventually come to a stop. 10a. In golf, the ball stays at rest on the tee until a force acts on the ball, which is the golf club. The ball returns to rest after another force acts on it. In hockey the puck remains in motion after being hit until a force such as another player, wall, or goal acts on the puck. In soccer, the ball stays at rest until a force (the kicker) kicks the ball, putting it into motion. The ball will come to a rest when it hits something or when there is friction between the ground and ball. 10b. Golf: Tiger Woods hit the golf ball off the tee, bringing the ball into motion after it was at rest. The ball was hit poorly, and the ball hit a tree, making the ball come to rest again. Hockey: Wayne Gretsky stopped the puck that was sliding across the ice. He aimed the puck at the goal and shot, bringing the puck into motion again. Unfortunately for Wayne, goalie Martin Brodeur was able to prevent the puck from going into the goal by catching the puck while it was in motion, bringing the puck to rest. Soccer: David Beckham had the ball at rest and in his possession, so he got ready to shoot the ball into the goal. Beckham brought the ball into motion by kicking it in the direction of the goal. The ball's motion was disturbed and brought to a stop after the goalie caught the ball before it went into the goal.

PTG # 5-9
5. 2.5 + 4.5 = 7m/s 6. 4.2 + 10.3 = 14.5m/s 7a. 5.6 + 2.4 = 8m/s 7b. 5.6^2 + 2.4^2 = c^2 c = 6.1m/s 7c. 5.6m/s + 0 = 5.6m/s 8. 85-18=67m/s 9a. sin angle = 15 / sin(45) = 21.2cm 9b. sin angle = 15 / sin(20) = 43.9cm 9c. sin angle = 15 / sin(15) = 58cm 9d. sin angle = 15 / sin(5) = 172.1cm

What Do You Think Now?
1. They keep on moving because there is very little friction because of the ice. Since there is no friction, the skater simply keeps on moving. The same effect happens for hockey pucks on ice. After being hit, they keep on gliding. 2. The ball continues to roll because there is not enough friction to bring the ball to a stop. The ball will eventually stop, but it will take a while for it to completely stop.

Inquiring Further #2
http://answers.yahoo.com/question/index?qid=20100518215527AAiUU2m In baseball, many players slide into second, third, and home, but almost never slide into first base. The reason why they slide into bases is usually to prevent being tagged out. If they are not forced to go to a base but go anyways, then the defensive player has to actually tag out the player. The slide helps prevent being tagged because you are lower to the ground, so it makes it harder for the player to actually tag you out. When going to first base players usually don't slide because they are forced to go to that base and do not have to avoid being tagged. It is simply a race to the base, and if the ball gets to the base before you do, you are out. Players can try to tag you out, but it's not recommended because it is much easier to step on first base than to tag a player running to first base. Also, you usually do not slide because it is faster to run than to actually stop running and slide.

= Section 2 =

What Do You See
I see in the top picture a person walking calmly and daydreaming, as shown by the "z", as he is walking. Since he is walking slowly, his footsteps are very close together. In the bottom picture the person is very awake and is running to his lover, as shown by the heart. Since he is running and moving at faster speeds, his footsteps are much farther apart because his strides are much larger.

What Do You Think
100mi/h means that in one hour, the ball would travel 100 miles in a frictionless environment where it would keep a constant speed of 100mi/h forever. 45m/s means that in one second, the ball would travel 45 meters in a frictionless environment where it would keep a constant speed of 45m/s forever. When something travels this fast in such a small distance, it is definitely hard to hit the ball well. First, you have to decide if you think the ball is in the strike zone. Then, you have to swing. The decision about swinging the bat depends on how fast your reaction time is. Athletes in sports such as baseball need good reaction times because they need to be able to swing fast enough without taking too long to decide to swing or not. Baseball is a tough sport, and when something travels nearly 100mi/h or 45m/s in such a small distance, it just gets harder.

Physics Talk Summary
-by looking at the distance between the dots made by the ticker time you can see acceleration, deceleration, and constant speed. -you can also tell if they were moving fast, slow, or in the middle -at constant speed, the distances between the ticks were equal in length -when traveling slow, the ticks are closer together -when traveling fast, the ticks are farther apart -you cover a greater distance moving faster than slower -during acceleration, the distance between the ticks are not equal -in positive acceleration, the ticks start closer and gradually spread apart -in negative acceleration, the ticks start farther and gradually become closer -a way to measure motion is to calculate speed -Vav = d/t -d is distance -t is time -instantaneous speed = the speed at a given moment -a = v/t -a is acceleration, v is velocity, t is time

Checking Up
1a. the dots are an equal distance apart 1b. the dots start off close and gradually spread apart 1c. the dots start off farther apart and gradually become closer 2. v = d/t = 400/50 = 8m/s 3. Instantaneous speed is the speed at a certain time and average speed is the total distance divided by the total time. 4. Vi = 0, Vf = 100km/h , t = 10s x 1h/3600s = .0028 , a = ? a = (Vf - Vi )/ t = (27.8 - 0) / 10s = 2.78m/s^2

Investigate
4a. Yes, there is a trend in the lengths of the paper segments of my graph. My graph was accelerating, and the lengths went from shortest to longest. 4b. The lengths of each paper segment tell me how fast I went during the 1/10 second. When the papers were smaller, I could tell I did not travel as fast since the dots were closer together. The longer the papers got, the faster I traveled. 5a.
 * Segment || Length ||
 * 1 || 1.3cm ||
 * 2 || 1.3cm ||
 * 3 || 1.35cm ||
 * 4 || 1.8cm ||
 * 5 || 2.2cm ||
 * 6 || 2.3cm ||
 * 7 || 2.5cm ||
 * 8 || 2.7cm ||
 * 9 || 3.1cm ||
 * 10 || 3.8cm ||


 * Segments || Acceleration ||
 * 1-2 || 0cm ||
 * 2-3 || .05cm ||
 * 3-4 || .45cm ||
 * 4-5 || .4cm ||
 * 5-6 || .1cm ||
 * 6-7 || .2cm ||
 * 7-8 || .2cm ||
 * 8-9 || .4cm ||
 * 9-10 || .7cm ||

5b. I was always accelerating, but it was not constant. The change in the length was always changing. For example, at one point the difference was only .05cm, while at another point the difference was .7cm. There was always positive acceleration, but it was not constant. 6a. In each graph, the pattern was different. In one graph, deceleration was occurring, so the lengths of each segment were becoming smaller and smaller. The other graph was constant speed. The lengths varied, but not by much. In the last graph, which was mine, acceleration occurred. Each segment in the graph became longer. Overall, each graph had a different pattern. 6b. In Megan's graph, the speed was supposed to be constant, but random errors caused the speed to be not perfectly constant. From segments 1-2, the speed stayed pretty constant, with no acceleration occurring. From 2-3, there was negative acceleration, caused by the random errors. From segments 3-6, positive acceleration occurred, so the segments became longer. From segments 6-9, negative acceleration occurred, so the segments became shorter. From 9-10, there was practically no acceleration, so the segments stayed just about the same length. From 10-11, positive acceleration took place again. Finally, from 11-12, a very small amount of positive acceleration took place.

PTG #1-4, 14
1. Instantaneous speed is the speed at a certain time and average speed is the total distance divided by the total time. 2a. 1km/15s = 1000m/15s = 66.7m/s 2b. 84m/6s = 14m/s 2c. 9.6km/2h = 9600m/7200s = 1.3m/s 4.8km/h 2d. 400km/5h = 400000m/18000s = 22.2m/s 89km/h 3a. negative acceleration since the fall brings the runner to a stop, and the runner has to negatively accelerate to come to a stop. 3b. positive acceleration since the runner starts not moving and eventually starts moving faster and faster. 3c. no acceleration 3d. negative acceleration since the ball is brought to a stop, and the ball has to negatively accelerate to come to a stop. 3e. no acceleration 3f. no acceleration 4a. A&D 4b. B 4c. A 4d. C 4e. a) + b) 0 c) + then - d) + 14a. When a person runs at the same speed throughout the whole lap around a track 14b. When a NASCAR driver drives at the same speed throughout the whole lap around a track 14c. When a person walks at the same speed throughout the whole lap around a track 14d. When a person starts walking but eventually starts running 14e. When a person is running but eventually comes to a stop

PTG #6-11
6a. a= (0-45km/h) / 9s = (0-12.5m/s) / 9s = -1.4 m/s^2 6b. negative 7a. constant motion 7b. positive acceleration 7c. slow constant, then positive acceleration, then faster constant, then negative acceleration, then slow constant 7d. negative acceleration, then constant, then positive acceleration 8. 100mi/2h = 50mi/h 9. It does not mean that because instantaneous speed is the speed at a certain time and average speed is the total distance divided by the total time. It is possible that the instantaneous speed is always 15m/s, but it is not likely. 10. . . . . . . . . . . 11. second 1 = 0 + 4m/s = 4m/s second 2 = 4m/s + 4m/s = 8m/s second 3 = 8m/s + 4m/s = 12m/s second 4 = 12m/s + 4m/s = 16m/s second 5 = 16m/s + 4m/s = 20m/s

What Do You Think Now
100 mi/h means that in one hour, you can travel 100 miles. 45m/s means that in one second, you can travel 45 meters. These speeds are based on a frictionless environment where no forces are acting on the object traveling at these speeds. In a frictionless environment, nothing can slow down or speed up the object moving, so it would stay at the same speed forever.

Physics Plus
Rebounding = bouncing off a surface and changing direction *assume acceleration is constant throughout entire process 3 stages of process: -falling down to ground -compresses until stopping -bouncing back up 1. a = (Vf-Vi) / t a = (.5 - (-.5)) / 1 = 1m/s^2 a = (.5 - (-.5)) /.1 = 10m/s^2 a = (.5 - (-.5)) / .01 = 100m/s^2 *The harder the surface of the object is, the less time it takes to rebound You may have small velocities, but the quicker the rebound, the greater the acceleration 2. a = (Vf - Vi) / t a = (.5 - (-.5)) / .2 = 5m/s^2 3a. 5m/s^2. It is going downward at this acceleration 3b. 5m/s^2 3c. 5m/s^2. The acceleration is the same at all 3 stages of the process
 * velocity || acceleration || examples ||
 * small || small || golf cart ||
 * small || big || rebound ||
 * big || small || big truck ||
 * big || big || airplane ||
 * In a v/t graph, the slope (acceleration) is a straight line since the acceleration is constant. The slope is 5m/s^2

=Chapter 2 - Section 3=

What Do You See
The person on the left is moving at a very slow speed, so the ball in front of her is not moving fast either. The person in the middle is moving faster, so the ball is moving faster. The person on the right is moving the fastest since she is sprinting, so the ball is going the fastest as well compared to the other two people and balls. Next each person is a small dog. The person walking has a dog walking slowly next to her. The middle person has a dog running next to her. The person on the right is in a car driving fast, so the dog is going the fastest in the picture on the right.

What Do You Think
A force is something that affects the movement of an object. In tennis, force is used to hit every shot, such as serves, forehands, backhands, and volleys. For example, in the serve, the ball is tossed up into the air, and the player bends and then jumps to hit the serve as hard as possible. The way the player uses his force makes the ball go very fast. The ball also goes faster since the ball is not very big and also is very light, weighing about 2 ounces. A bowling ball would not move very fast if it was hit since it is much bigger and heavier. Since the mass is greater, you need more force to make the bowling ball move. Since the tennis ball is light, you do not need as much force to make it move.

Physics Talk Summary
-Newton's second law equation is acceleration = force/mass -force is in Newtons and mass is in kg. -F = m x a  -a = F/m -m = F/a -N = Newtons -1N = 1kg x m/s^2 1kg x m/s^2 = 1kg x m/(s x s) -Newton's second law states that accelerations are caused by unbalanced forces. -If there is acceleration, then an unbalanced force must be causing the acceleration -when force is applied to a small object, the acceleration will be large -when a force is applied to a big object, the acceleration will be small -Newton's second law is always valid -the number of significant figures shows how precise the measurements were -all nonzero numbers are considered to be significant figures -zeros may or may not be significant, depending on their place in a number -a zero between nonzero digits is significant -a zero at the end of a decimal number is significant -a zero at the beginning of a number is not significant -when adding or subtracting, the final number should have the same amount of sig figs as the measurement with the fewest decimal

Checking Up #1-4
1.Newton's second law states that accelerations are caused by unbalanced forces. 2. Increasing an object's mass lowers its acceleration. 3. 30N of gravity force are acting on the object. 4. I would be lighter on that planet, but my mass would stay the same.

Physics Talk 166-167
-another type of force is gravity -gravity pulls objects to the ground, which is why the ruler bend in the experiment we did -if there is an acceleration, an unbalanced force is acting on the object moving -weight- the force of gravity acting on an object -to calculate weight : Fgravity = MAgravity w=mg -m is mass in kg -g is acceleration due to gravity -when a force acts on an object, it accelerates -a free-body diagram is a diagram used to show the relative size and direction of all forces acting on an object -gravity acts on your hands when you stick them out -blue arrow represents force of gravity -red arrow is force of your hand -2 forces must be equal if object isnt accelerating.

PTG #1,3,4,5,9
1. a)70 x 5 = 350N  b)800/10 = 80kg c) 70/7 = 10m/s^2 d) 400/5 = 80kg e) -1500/100 = -15m/s^2 f) 100 x -30 = -3000N 3. f = m x a 42N = .3kg x a  140m/s^2 = a  4. f = m x a  f = .040kg x 20m/s^2 f = .8 N 5a. The balls were moving at a constant speed since no forces were acting on either ball. The person stopped the balls' motions by catching the balls. The person was the unbalanced force acting on the balls, and the person's force caused the ball to decelerate quickly and come to a sudden stop. 5b. The baseball was much easier to stop than the bowling ball. Even though the same amount of force acted on the ball, the bowling ball weighs more, so it is much harder to bring to a stop. 9. When the ball is many meters away, the force of my hand does not act on the ball. The second you let go of the ball, your hand stops acting on it

What Do You Think Now
A force is something that affects the movement of an object. The force causes the object to accelerate, and the more force there is, the faster the object will accelerate. If there is less force, the object will accelerate less. If the same amount of force was to act on a tennis and bowling ball, the tennis ball would accelerate much easier and the bowling ball would not accelerate as easy. This is because the bowling ball weighs much more than the tennis ball. If the mass is greater, you need more force to make it accelerate. Since the bowling ball has a greater mass and and same amount of force is on the tennis ball, the bowling ball will move less.

PTG # 10, 11, 12, 15, 18
10. 50N + 40N = 90N 11. 200N x 4 = 800N 12. f = m x a 125N = 700.0g x a  125N = .7kg x a  178.57m/s^2 15. f = m x a f = 12.8kg x 9.8m/s^2 f = 125.44N 18. In baseball, the more force you hit the ball with, the faster it will accelerate. If you decide to bunt the ball, which is when you simply put your bat out but do not swing, the baseball will not travel very far. This is because the ball did not accelerate fast, which was caused by the person at bat not hitting the ball with much force. If the player takes a full swing at the ball and hits a home run, it was caused by the player exerting a lot of force on the ball. Since the player hit the ball with a lot of force, the ball accelerated much faster, so the ball was able to travel farther. The more force that you hit the ball with, the faster the ball will accelerate.

**PTG #13, 14, 16, 17** 13. a^2 + b^2 = c^2 50N east ^2 + 120N north = c^2 2500N east + 14400N north = c^2 N northeast 130N northeast 14. 4000N south ^2 + 5000N ^2 west/east = c^2 6403.12N southeast/west 16. A=f/m A = 70N/5.6kg A = 10.8m/s^2 17a. 30N-20N = 10N to the left 17b. a = f/m = 10N / 100kg = .1m/s^2 17c. a = f/m = 50N / 100kg = .5m/s^2

Physics Plus #1-2
1. a = 125N west b = 125N east 125^2 + 125^2 = R^2 R = 176.78N tan^-1(125/125) = 45 degrees 2a. 70N -40N = 30N south 2b. 40N^2 + 40N^2 + 70N^2 = 8100 = 90N southwest 2.southwest

= Chapter 2 - Section 4 =

What Do You See
I see a person on a ladder dropping two apples. A person on the ground is timing how long it takes each apple to land. One apple is thrown on an angle and one is thrown straight down.

The height it was thrown at, the angle it was thrown at, and the forces acting on it while it is traveling affect how far an object thrown into the air travels before landing.

Investigate
1a. Yes, they both hit the floor at the same time. 2a. Yes, they both hit the floor at the same time. 3a. Yes, they both hit the floor at the same time, but after hitting the ground, the balls traveled farther. The speed does not matter. 3b. The faster the ball hits the floor, the farther the ball will travel. 3c. 4a. The height does not matter, so the balls hit the floor at the same time. 5a. I predict the ball will not come back to the thrower's hand. The thrower will move forward while the ball moves up, so when the ball comes back down, the thrower will be ahead of the ball. 6a. Vertical component of velocity decreases on the way up. Horizontal components of velocity do not change. Vertical components of velocity increase on the way down. 6b. If you stay at a constant speed the ball will come back to you but if you increase your speed the ball will not be where you want it, the ball will fall behind you.

Physics Talk Summary
-projectile motions are crucial to your voice overdub of sporting events -projectile - the only force is weight. Launched through the air. Ignore air resistance. -Trajectory - path of projectile. -Ground to ground launches are symmetrical around the highest point (Ymax) -x and y information are independent from each other -Ay = -9.8m/s^2 -Ax = 0 -if the two statements above aren't true, its not a projectile -Free fall- the only force to weight but 1 dimensional motion (only vertical) -vertical positions of free fall to projectile are same

Checking Up
1. Yes, they will both hit at the same time because they have the same acceleration. 2. It's velocity does not remain the same, it accelerates. 3. The ball's velocity at its highest point is 0 and its acceleration is -9.8m/s^2.

PTG #1, 2, 4, 6
1. O - - - - - O O - - - - - - - - O O - - - - - - - - - - - O O - - - - - - - - - - - - - - O 2. O - - - - - - - - - O O - - - - - - - - - - - - - - - - - - - - - O O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O 4. Everybody thought that the one that was dropped would hit the ground faster than the one that went horizontally because the horizontal angle it was shot at would make the bullet stay in the air longer because it is not going straight down, it is going horizontally while falling. 6. Horizontal motion has no effect on vertical motion, and vice versa. If you go 10mph right while moving 5mph up and then change to 15mph right, your vertical motion will not change. You will still be moving 5mph up even though your horizontal speed changed. If you changed your vertical speed, your horizontal will not change. For example if you are going 10mph right and up and change to 15mph up, you will still be moving 10mph right.

What Do You Think Now
Some factors that affect how far an object thrown into the air travels before landing are the initial height and velocity of the object being thrown. If the object starts at a higher initial height, it will take longer for the object to come back and hit the ground. If the object's velocity is faster, then the object will travel higher into the sky, meaning that it will take longer for the object to come back to the ground.

**Sports Video: Get Perfect Shooting Arc (basketball)**
[] 1. Horizontal and vertical motions play a major part in being able to shoot the basketball into the hoop. A perfect shot includes a high shot with enough vertical speed to reach the hoop. Shooting vertical is important because the ball needs to come down at a steep enough angle to make it into the hoop without bouncing off of the rim and not going in. If you do not shot with any vertical motion the ball will not go in because it will not be able to reach the height of the hoop. Since the ball needs to go in the hoop, the ball needs to be thrown higher than the hoop so then the ball can go into the hoop when coming back down to the ground. Horizontal motion is needed because without horizontal motion, the ball will only go up and then come back down, but will not travel to the hoop. The horizontal motion brings the ball to the hoop. A perfect shot needs a good height and a good amount of horizontal motion. 2. Throwing the ball with a good arch matters because you need the height and the horizontal motion. If you have too much or too little of either, the ball will not go in the hoop. Too much vertical motion and too little horizontal motion will result in the ball not reaching the distance of the hoop. Vice versa will result in the ball not reaching the height of the hoop. If you have the perfect amount of both, the ball will go in the hoop.

PTG #7-11
7. Arrow A will hit the ground quicker the arrow B even though they both were dropped at the same time from the same height. Arrow B is not going directly down so it will take longer for it to reach the ground. Arrow A's path to the ground is also shorter than arrow B's path to the ground. 8. 2^2 + 3^2 = r^2 3.6 = r tan^-1 (2/3) = 33.7 degrees 9a. velocity = 15 cos 37 = 11.98m/s 9b. 11.98 x 2 = 23.96m 10a. 12 cos 45 = 8.5m/s 10b. 8.5/2 = 4.2m 11. The pitcher pitches the ball at a velocity of 90 miles per hour. The batter takes a big swing and hits the ball with a force of 300N. The ball was hit with enough force to make it travel travel into the outfield. While the fielder accelerates to retrieve the ball that went by him, the batter sprints into second base and slides, ending with a double. The hard and long hit ball gives enough time for a runner, who started at second base, to score, giving the batter a run batted in, or an RBI. The fielder throws the ball back to the pitcher for the next at bat.

=Chapter 2 - Section 5=

What Do You See
I see a girl kicking a soccer ball into the air very high. The soccer ball travels behind her while going up and then coming back down, creating a parabolic shape, and then landing on another person's head. The ball deflects off of the person's head and goes into the goal. After deflecting off of the person' head, the ball creates another parabolic shape, except the ball does not go as high.

What Do You Think
The trajectories of projectiles vary based on the angle the object was thrown at. The higher the angle the higher the object will travel. In javelin, the javelin is thrown at a higher angle for more hang time and more distance. Since the javelin does not roll, the thrower needs to throw it at a higher angle and with as much force as possible. If the javelin thrower throws it too high up, the javelin will not travel as far, so the thrower needs to throw it high, but not at too high of an angle. In shot put the ball is thrown at an angle not as higher as in javelin. In shot put the ball is supposed to eventually roll after being thrown, so they throw it at a lower angle, but not too low, otherwise it will not go very far. It is not thrown too high because then the ball will not roll. In both sports, the faster you throw the object, the farther it will travel. If the javelin is thrown faster, it will take longer for it to return to the ground, resulting in a farther distance. If in shot put you throw the ball faster, it will stay in the air longer and be able to roll longer, resulting in a farther distance.

Physics Talk
-earth's gravitational force causes a downward acceleration of 9.8m/s^2 -if you use a computer or calculator to model trajectories of projectiles, then you can change variables such as launch speed, launch height, and range. -if you ignore air resistance, the path of all trajectories are parabolas -the higher your angle is, the higher the object will go, but it will land shorter -if your angle is smaller, then the object will not go as high, but will travel farther -example: an object shot at an 80 degree angle would go much higher than being shot at 40 degrees, but the object shot at 40 degrees would go farther than the object shot 80 degrees -all balls travel in parabolas -45 degree angles produce the greatest range -range= distance -small angles have greater horizontal velocities but have a shorter hang time -baseball and golf balls do not always follow true parabolic paths -air temperature also affects the distance a ball will travel

Checking Up #1-3
1. The two types of motion that help you understand the trajectory of a projectile are constant speed along a straight line and downward acceleration at 9.8m/s^2. 2. The fundamental requirement needed is that the model must match reality in nature. 3. If the angle of launch is increased from 10 to 80 degrees, the object will be launched higher, but will land shorter.

Physics Plus
all answers are on photo

PTG #1-10
1. 45 degrees produces the greatest because it will not be too high or too low, its right in the middle, so it gets enough height but not too much. 2a. The object will spend more time in the air 2b. The object will spend less time in the air. 3a. 60 degrees 3b. 75 degrees 4. Their distance is much more important than their height. Therefore the angle has to be less than 45 degrees. 5. Vix HIGH + his Dymax is HIGH 6a. a = -g = -9.8m/s^2 down 6b. Vmax = Vix since Vy = 0 at the maximum height. Since the ball is not moving anymore upwards at point x, Vmax = Vix 7a. Vi =5m/s Vf = Vf d = unnecessary a =-9.8m/s t = 3 Vf = Vi + at Vf = (9.8)(3) Vf = 29.4 m/s

7b. Vf = Vi + at Vf = 5 +(0)(1) Vf = 5m/s

7c. d = vt d = (5m/s)(3s) d = 15m

8. 45 degrees 9. 90 degrees 10a. -9.8m/s down 10b. Vi=20m/s Vf= not needed d= 100m a=-9.8m/s t= t d = Vit + (1/2)at^2 -100 = -4.9t^2 4.5s 10c. d=vt d = 20(4.5) d = 90m

What Do You think Now
If you shoot an object at a higher angle, such as 80 degrees, the object will go higher, but land shorter. If you shoot an object at 40 degrees, the ball will not go up as high, but will travel farther. A faster launch speed will make the ball go higher and farther, meaning the ball will also have a longer hang time. If you have a slower launch, the ball will travel shorter and not go as high, even though it was shot at the same angle.

Physics Practice Test #1-9, 19, 22
1. b 2. d  3. c  4. a  5. c  6. c  7. d  8. c  9. a  19. 22. v = d/t 15 =d/5 3m = d

= Chapter 2 - Section 6 =

What Do You See
I see a person sitting in a chair pushing off of a wall. He was at rest before he pushed off the wall, but when he pushed on the wall, his body and chair went in the opposite direction. It pretty much looks like the wall pushed him back.

What Do You Think
If I met a person that wanted to learn how how jump, I would tell him to exert downward force to the ground. If you push on something that you are not able to move, your body will move in the opposite direction. Since you are pushing on the ground and you are not able to move it, your body will move up, which is a jump.

Physics Talk
-an acceleration is always accompanied by an unbalanced force -Newton's 3rd Law of Motion states that for every applied force, there is an equal and opposite force -the law also states that forces always come in equal and opposite pairs -if you push on a wall, then the wall will return the same amount of force back -the law always acts on different objects -you cannot touch someone without them touching you back -when a meter stick bends, it provides a force -free-body diagram- a diagram that shows the forces acting on an object -mass pulls you down -a free-body diagram shows the strength and direction of all forces -each force is represented by an arrow -center of mass- the point of an object in which the mass is considered to be concentrated -to every action there is an equal reaction

class notes: Newton's 3rd Law *for every action, there is an equal but opposite reaction. *All forces come in pairs. Each acts on a different system. They must be EQUAL in size but point in opposite directions

Force of A on B = Force of B on A A is a truck, B is a car Fa = Fb MaAa = MbAb 1000 x .01 = 10 x 10

Checking Up #1-3
1. Newton's third law states that for every applied force, there is an equal and opposite force. 2. The equal force is gravity and the opposite force is the ground. 3. A free-body diagram is a diagram that shows the forces acting on an object.

PTG
1. Yes, the force is equal and in the opposite direction because the forces must be equal to each other since the forces are both associated with the same 2 things, the ball and the hand. 2. The chairs do not have any intelligence, but they have the same effect as the ground. If you push on the ground, the ground will return a force equal to yours and opposite to your weight. When you push on the chair, the force you create will go through the chair and into the ground. Then, the ground will return a force equal to yours and opposite to your weight. The force that the ground creates will go through the chair again and then back to you. Overall, there is a deflection involved. No... but "restoring" forces balance downward weight. 3. The scale measures how much force you are exerting on it. The scale acts as if it was the ground, except the scale actually measures your force. If you are heavy, you will put more force on the scale, so the scale will show a larger number as your weight. Spring with needle attached, calibrated. 4. The two forces are equal to each other, but the forces are in opposite directions. Sometimes the bat will break because the force of the baseball is too big for the bat to withstand. = but opp. break because Fball is too big for material to withstand 5. When a big linebacker tackles a small running back, the running back will feel the force of the linebacker. Since the linebacker is heavier, he will exert more force on the running back than the running back will on the linebacker. Since the linebacker is heavier, he will knock down the small running back. = but opp. The smaller player has bigger accel. 6. The force of the boards on the player and the force of the player on the boards are active. These forces are equal to each other, but are in opposite directions. Fboardsonplayer = -Fplayeronboards 7. When players use equipment such as baseball mitts, the padding of the glove helps lower the acceleration of the baseball. Since the ball is slowed down by the padding, there is less force on the player's hand. Padding causes lower acceleration which reduces force on hand. 8a. In physics, if you put force on the ground, the ground will return the same amount of force back at you. I can make this more exciting by putting it in a conversation in a sportscast during my sports movie project. 8b. The ground produces a force when something is forced to the ground. If something puts force on the ground, the ground will return the same exact amount of force that put force on the ground.

What Do You Think Now
When you jump, your force should be to the ground. The ground will return the same amount of force back at you. The more force you put on the ground, the higher you will jump. Also, a normal force goes in a vertical direction, from the ground to the sky. Your mass does not matter when jumping since the ground will return an equal force, but when you weigh less, you have a faster acceleration.

=Section 7=

What You You Think
I think that sports require certain shoes because in some sports you need to slide, while other sports you need to do other things. Bowling shoes have less friction than regular shoes, which is why you can slide in them. You cannot slide in cleats because you need friction in order to run on the dirt or grass without slipping.

Physics Talk
-you can measure force with a spring scale -the reason that the shoe did not accelerate horizontally was because of friction between the shoe and the surface -the force I applied was equal to the frictional force -we actually measured the pulling force but used it as the frictional force -pulling and frictional forces are equal in strength -in the investigate, the shoe did not move vertically -the force perpendicular to the surface is called the normal force -the normal force is in the opposite direction of the shoe's weight -the coefficient of sliding friction = force of friction / perpendicular force exerted by the surface on the object (normal force) = Ff / Fn -The Coefficient Of Sliding Friction: -does not have any units -is usually in decimal form -is valid only for the pair of surfaces in contact when the value is measured; any change in surface may cause the coefficient of sliding friction to change

Checking Up #1-3
1. Since the two are equal, their net force is zero, which shows that they are equal. Also, the forces go in oppsite directions. 2. It has no units because it is a force divided by a force. 3. To find the coefficient of sliding friction, the equation is force of friction / perpendicular force exerted by the surface on the object (normal force).

PTG #1-5
1. In tennis, you want to have friction between you and the ground so you can run and change directions when necessary. If the courts are wet at all, then there will be less friction. You will slide much more and most likely lose control of your balance if you run too fast. There is not much that you can do in tennis since you must wear tennis sneakers, so if the courts are wet, the best thing to do is stop playing before you fall and hurt yourself. 2. In skiing, people reduce their friction by putting wax on their skis. With less friction you are able to travel on the snow much easier. 3. Since not every court is the same, she cannot be sure. If she went to play somewhere else, such as an outdoor court with some water on it, she will want more friction because the water will reduce friction. No two courts are the same, so her shoes will not be perfect for every court. 4. Tennis players have different shoes for different surfaces because the surface of the court affects how much friction you will have with the court. You can slide on clay courts because you have less friction on the court than you would on a hard court. Shoes for clay or grass will be made to provide extra friction between the player and the court to prevent them from slipping. 5. .03 = Ff / 600N Ff = 18N

PTG #7-8, 10-11
7. The forces of air and water resistance do change when speeds change. For example, it is much easier to stop water's motion when it is coming out of a sink than it is to stop water coming out of a fire truck hose. 8. When there is a maximum frictional force, there definitely is a limit on how fast you can start. If there is a maximum, then you cannot go above the maximum. Buying shoes with a much smoother sole will solve this problem. 10. Friction is important in running because friction allows you to push off of the ground and accelerate. Without friction you cannot accelerate. Cleats are used for extra friction. Therefore, cleats allow you to accelerate much faster. 11. The runners are lining up at the starting line for the race. The runners a getting into a good starting position. To accelerate, the runners will use the friction between themselves and the ground. The runners have spikes on the bottom of their shoes for extra friction, which means they will have the ability to accelerate faster. And they are off, and accelerating very fast.

Physics Plus


∑Fx = MAx Wx - Fx = MAx mgsin30 - f = MAx (1.5)(9.8)(sin30) - f = (1.5)(0) Fs = 7.35N

∑Fy = MAy N - Wy = MAy N - Wy = 0 N = Wy N = mgcosø N = (1.5)(9.8)(cos30) N = 12.73N

µ = f/N µ = 7.35/12.73 µ = .58

PTG #6
a. w=mg w=1000 x 9.8 w = 9800 N

b. µ = f/n .55 = f/9800 f = 5390N

c. Fx = MAx f = ma -5390 = 1000a a = -5.390m/s^2

d. Vf = Vi + at 0 = Vi +-5.39(6) Vi = 32.34 m/s; change in speed

e. The claim was incorrect since the original speed was 32.24m/s. He had to stop shorter since his speed was fast, which is why speeding is a bad thing. When coming to a stop, he decelerated at 5.39m/s^2 for 6 seconds.

What Do You Think Now
Some sports require different shoes because in some sports you need to have extra or less friction than normal. Some sports use cleats to help you get extra friction with surfaces such as dirt and grass. In bowling, the shoes have a different surface to help you slide. You slide because you have less friction with the ground.

Part 1
1. 1.85N tension 1: 4.4N tension 2: 4.8N tension 3: 4.8N Ff : 4.7N Total Weight: 11.65N µ: .40 Class Average µ: .33 Class Data: % difference: 21%
 * Tension(N) || Ff(N) || Total Weight (N) || µ || Class Average µ || % difference ||

Calculations: ∑Fx = MAx T-f = 0 T=f

∑Fy = MAy N-W = 0 N = w 11.65 - N = 0 N = w = 11.65

µ = f/n µ = 4.7/11.65 µ = .40

% diff =(( | Avg - yours|) / (Avg)) x 100 = ( |.33-.4| / .33) x 100 = 21%

Part 2
Calculations:
 * Mass (g) || Mass (kg) || Measured Time (s) || Measured Distance (m) || Ff (N) || Acceleration (m/s^2) || Calculated Vi (m/s) || Calculated time (s) || % error ||
 * 240 || .240 || 2.05 || 6.69 || .78 || -3.25m/s^2 || 6.59m/s || 2.06s || 20% ||
 * 240 || .240 || 2.09 || 6.95 || .78 || -3.25m/s^2 || 6.72m/s || 2.1s || 22% ||
 * 240 || .240 || 1.97 || 6.51 || .78 || -3.25m/s^2 || 6.50m/s || 2.03s || 19% ||

∑Fx = MAx -f = ma -.78 = .240a a = -3.25m/s^2

∑Fy = MAy N - w = 0 N = w N = mg  N = .240 (9.8) N = 2.352N

µ = f/n .332 = f/mg .332 = f / (.240 x 9.8) .78 = f

14. Vf^2 = Vi^2 + 2ad 0 = Vi^2 + 2(-3.25)(6.69) Vi^2 = 43.485 Vi = 6.59m/s

Vf^2 = Vi^2 + 2ad 0 = Vi^2 + 2(-3.25)(6.95) Vi = 6.72m/s

Vf^2 = Vi^2 + 2ad 0 = Vi^2 + 2(-3.25)(6.51) Vi = 6.50m/s

15. Vf = Vi + at  0 = 6.59 + -3.2t t = 2.06s

Vf = Vi + at 0 = 6.72 + -3.2t t = 2.1s

Vf = Vi + at 0 = 6.50 + -3.2t t = 2.03s

17. % error = (2.06-1.64) / 2.06 = .20388 x 100 = 20% % error = (2.1 - 1.64) / 2.1 = .219 x 100 = 22% % error = (2.03 - 1.64) / 2.03 = .192118 x 100 = 19%

Part 3: Questions/Conclusion
1. The coefficient of friction in Part 1 represents the friction between the block and the floor. 2. While my µ was .40, the class average was .33. My results should not be the same as everyone else's, but should not be very far off. Errors take place during experiments, such as reading measurements incorrectly, which is one factor that might make results vary. We get a class average by averaging together every group's results, and my results contributed to the average, but is higher than the average because other groups' results were lower than mine. 3. My percent error was 21%, which is not the best percent error. If the percent error was smaller, my results would have looked better compared to the rest of the class. 4. The theoretical physics we are doing in class does seem to apply to the real world. One example would be sneakers or cleats in sports. When the sole of the sneaker is rougher, you have more friction with the ground, which slows you down faster. When you wear shoes such as bowling shoes, you are able to slide since the shoes do not dig into the ground as much as other shoes. When you wear cleats, you cannot slide and you stop easier since the shoes dig into the ground much more than other shoes. 5. 3 sources of experimental error are friction of floors are different, reaction time of timer, and tape might not be in a straight line. If the friction of floors are different, the block might travel farther on one floor than another. If the reaction time of the timer is slow, then your times will definitely be incorrect. If your tape is not in a perfectly straight line, then your measurements for how far the block traveled will definitely be incorrect.

= Section 8 =

What Do You Think
They might not be able to because the longer pole might bend more, therefore not adding 11 meters to the vaulter's jump. The shorter pole will bend less, so the vaulter might have an easier time clearing the 6m jump. The pole's bending and the speed of the vaulter running can affect the vaulter's height.

Investigation
Prelab 1a. Bending the ruler while it is horizontal. 1b. -The deflection of the ruler (force, elasticity) -length of ruler -placement of object -mass of object 1a. I will be able to conclude that the object will go higher when you use the same amount of force if you fling the object from the end of the ruler than the middle. 1b. I will record the heights of the penny after being flung from different parts of the ruler. 1c. The tools we will be using are a penny, a ruler, and a meter stick. 1d. We will analyze the data by trying to find patterns in the heights of the penny after being flung from different parts of the ruler. We expect the penny to shoot up higher when it is flung from the end of the ruler and not shoot as high when we move the penny closer to the middle of the ruler. Investigation 8: Height of a Pole Vaulter Variable Tested: Height of the penny after being flung from different parts of the ruler. Methods and Materials: penny, ruler, meter stick We put the penny in different spots on the ruler and launched it using the same amount of force in each launch to see how high it would go. Data Table:
 * from end of ruler (cm) || from halfway from middle of ruler (cm) || from middle of ruler (cm) ||
 * 90, 95 || 45, 55 || 20, 15 ||

Conclusion: I can conclude that the penny will go up to different heights if you use the same amount of force but place the penny in a different spot on the ruler. When the penny is closer to the end of the ruler, the penny will go up much higher than when you use the same amount of force when flinging but put the penny in a spot closer to the middle of the ruler. Group member names: Jason Prezant, Megan Lynch

Physics Talk
-when a force acts on an object, the speed and position of the object may change -when a ball is thrown vertically, it slows down because of the gravitational forces acting in the opposite direction of the ball's movement. Then, when the ball moves downward, it accelerates because the gravitational forces are giving it some extra force. -a force can change the position and speed of an object in a way that allows the position and speed to change back -the concept of energy was developed to identify what was not changed in these situations -kinetic energy- energy associated with motion -gravitational potential energy- energy associated with position -potential energy- the total energy -When forces act on objects, energy changes from one form to another, but the sum of kinetic and potential energy remains constant. -law of conservation of energy- the concept that the total energy remains constant -while a ball is rising or falling, the sum of the gravitational potential energy and the kinetic energy remains constant -work- a precisely defined physics quantity that equals the force multiplied by the distance. -whenever work is done, the energy of an object changes -the coin investigation we did is a good example of work and conservation of energy -elastic potential energy- the energy of a spring due to its compression or stretch -a good example of the law of conservation of energy is pole vaulting -the forms of energy are changed, or transformed, from one to another during a vault, but, in principle, the total amount of energy in the system of the vaulter and the pole remains constant -food energy provides muscular energy for the vaulter to run, gaining an amount of kinetic energy -some of the vaulter's kinetic energy is used to catapult the vaulter with an initial speed upward and the remaining kinetic energy is converted into an amount of elastic potential energy as the vaulter does work on the pole as it bends. -As the pole straightens, its elastic potential energy is transferred to the vaulter to increase the vaulter's gravitational potential energy as the vaulter's height increases. -work done equation is W = F x d -elastic spring potential energy equation is EPE = (1/2)kx^2 -gravitational potential energy equation is GPE = mgh -kinetic energy equation is KE = (1/2)mv^2 -the unit of work or energy is called the joule (J)

Class Notes

 * Type Of Energy || Description || Equation ||
 * Kinetic Energy || Energy possessed by an object when it is moving || KE = 1/2mv^2 ||
 * Gravitational Potential Energy || Energy possessed by an object when it is above its lowest point || GPE = mgh ||
 * Elastic Potential Energy || Energy Possessed by a spring when stretched or compressed || EPE = 1/2 k x^2

k = spring force constant

x = distance stretched or compressed ||
 * Work || Caused by a force acting over some distance parallel to the direction of motion. Not really "energy", but creates energy. || W = F * d ||

The Law of Conservation of Energy- Total Energy remains constant but the types of energy can change.

Checking Up
1. Force is required for the energy of an object to change. 2. The penny gets its energy from the ruler's elastic potential energy. 3. The pole vaulter gets the energy needed to bend the pole and then rise over the bar from kinetic energy 4. The units for work, kinetic energy, gravitational potential energy, and spring potential energy are joules, or J.

PTG #1-16
1. Work is done in shot put because the thrower puts his force parallel to the direction that the shot put is moving in. The shot put moves over a distance that was parallel to the direction of the force that the shot putter put on the shot put. The work is changed to kinetic which is changed to gravitational to kinetic to Work out. 2. You build potential energy, then you use elastic potential energy to wind up, which turns to kinetic energy, which turns to work on the ball. 3. KEi = GPEf (1/2)mv^2=mgh (1/2)v^2 =gh h = 7.3m 4. The length of the pole does not determine the vaulter's limit because the pole also possesses elastic potential energy when it bends. The more it bends the higher the jumper will go. Also, the jumper possesses kinetic energy when moving. The jumper will use the energy to get a little extra boost when letting go of the pole. Overall, the vaulter's limit is not determined by the length of the pole. Also, your initial speed before vaulting plays a major role in your maximum height. 5. When the temperature of the pole increases, heat steals energy, lowering your maximum possible height. 6. (1/2)mv^2 = mgh (1/2)v^2 = gh .5v^2 = 9.8(4.55) v = 9.5m/s 7. Bubka must have been running faster than Emma George because when you run faster, you hold more kinetic energy. Bubka used the kinetic energy and turned it into gravitational potential energy, which is also what George did. Since Bubka had more kinetic energy, he went up higher than George. 8a. GPE = KE mgh = .5mv^2 (9.8)(100) = .5v^2 v = 44m/s 9a. W = EPE = .5kx^2 = .5(1500)(.25) = 47J

9b. EPE = KE .5kx^2 = .5mv^2 47J = .5(.1)v^2 31m/s = v

10a. W = EPE W = .5kx^2 = .5(315)(.3)^2 = 14.2J

10b. Fd = .5kx^2 F(.3) = 14.2J F = 47.3N

11. GPEi = EPE mgh = .5kx^2 (.04)(9.8)(1) = .5(18)(x^2) x = .21m

12a. F = ma N = Kg * m/s^2 12b. GPE = mgh = (kg * m/s^2) * m = N * m  = J  12c. KE = .5mv^2

=Kg(m/s)^2= (Kgm^2)/s^2

= N * m 12d. EPE = .5kx^2 = (N/m)(m)^2 = N * m 13. The diving board's EPE makes the diver go up into the air. The diver has GPE when she is up in the air. The diver has KE when she is moving in midair. 14. The ball requires work to get moving, but turns into gravitational potential energy and kinetic energy when it is in midair. 15. When the pitcher throws the ball, he is doing work. The ball gains kinetic and gravitational potential energy since the ball is moving and it is off the ground. When the player hits the ball, he is also doing work since his force is in the opposite direction. The force that he puts on the ball makes the ball makes the work turn into gravitational potential and kinetic energy. 16. The soccer player does work by getting the ball to move. The work turns into gravitational potential and kinetic energy since the ball goes off of the ground and gains speed. The goalie brings the ball to a stop by doing work on the ball when he puts his force in the opposite direction of the ball's motion.

What Do You Think Now
They might not be able to vault over a 12.0m high bar with a pole 11.0m long because the pole might end up taking up more energy to bend extra, so your maximum height might be lower.

= Section 9 =

What Do You Think
I think they cannot learn how to stay in the air longer than a normal human. Just because they are good athletes does not mean they can stay in the air for extra time. The athletes try to do as many tricks as they can while they are still in the air, which is the same amount of time as any other person.

Physics Talk
-work is equal to the product of the applied force and the distance -when you are in ready position, you have elastic potential energy -chemical reactions in your muscles create the elastic potential energy -the energy during a jump d=is shown in the graph below -the energy of each position must be equal. -the launch position have gravitational potential and kinetic energy -ready position has elastic potential energy -peak position has gravitational potential energy -the conservation of energy is a unifying principle in all science -something similar to jumping on a hard floor is jumping on a trampoline or bed -if you were to jump on a trampoline, the potential energy from the height you are jumping would provide kinetic energy when you landed on the trampoline. As you continued down, you would continue to have kinetic energy because you would still be losing gravitational potential energy. However, the trampoline bends. -there are many different types of energy, and all of them can be measured and calculated -the conservation of energy means that the total amount of energy at one time must be equal to the amount of energy at another time -in soccer, the amount of energy that a player loses is equal to the amount of energy that the ball gains -the ball gains energy because work was done on it -the foot lost energy because negative work was done on it

Checking Up
1. The energy comes from the elastic potential energy of the ready position turning into the gravitational potential energy and kinetic energy of the launch position. 2. In launch position there is gravitational potential energy and kinetic energy. In peak position there is only gravitational potential energy. 3. Other types of energy include electric energy, sound energy, and light energy.

Physics Plus
1. GPE = KE + GPE mgh = .5mv^2 + mgh (9.8)(50) = .5v^2 + (9.8)(30) 490 = .5v^2 + 294 196 = .5v^2 392 = v^2 19.8m/s = v

2. "How fast is the balloon going when it hits the ground?" GPE + EPE = KE mgh + .5kx^2 = .5mv^2 (.3kg)(9.8)(2) + .5(60)(.4)^2 = .5(.3)v^2 5.88 + 4.8 = .15v^2 10.68 = .15v^2 71.2 = v^2 8.4m/s = v

3. GPE + Win = KE + GPE +Wout mgh + F * d = .5mv^2 + mgh + F * d 200(9.8)(25) + 200000 = .5(200)(40)^2 + 200(9.8)h + 50000 249000 = 160000 + 1960h + 50000 39000 = 1960h 19.9m = h

Investigate
Prelab 1a. 20 1b. 2/3 s 1c. No 2a. 1s 2b. No Lab 1. W = GPE 2a. The more force you exert on the ground, the higher you will go. 2b. We will record starting point of the hips when you are bent, when you are not bent, and how high you jump. 2c. We will use a meter stick. 2d. We will analyze our data by seeing how high we go compared to how much force we exert on the ground. 3. Not bent: 100cm Bent: 80cm Jump Height: 45cm W = GPE Fd = mgh F(.20) = (616.7)(.65) F = 2004.3 N

PTG
1. W = GPE W = mgh W = (50)(9.8)(1) W = 490J 2. Work is used to get the bobsled moving from rest. Then, the bobsled gains kinetic energy since it is moving. To bring the bobsled to a stop, work is used again. The bobsled is stopped since the force is in the opposite direction of the motion of the bobsled. 3. We would see if the statement is correct by looking at how high his feet were in each frame. The results would show that the player does not hang in the air. 4. They should definitely give proof of their information, even though their information is not true. Someone else with more knowledge should prove them wrong. In the end, they will both have the burden of proof because the person with false information will try to prove themselves right, while the person with more knowledge will try to prove the other person wrong. 5. An athlete can jump better by losing weight or gaining muscle to push off of the ground with more force. 6a. W = F * d W = 1N x 1m W = 1J 6b. W = F * d W = 1N x 10m = 10J 6c. W = F * d W = 10N x 1m = 10J 6d. W = F * d W = .1N x 100m = 10J 6e. W = F * d W = 100N x .1m = 10J

7a. W = GPE W = 1N x 1m = 1J 7b. W = GPE W = 1N x 10m = 10J 7c. W = GPE W = 10N x 1m = 10J 7d. W = GPE W = .1N x 100m = 10J 7e. W = GPE W = 100N x .1m = 10J

8a. KE = GPE KE = 1N x 1m = 1J 8b. KE = GPE KE = 1N x 10m = 10J 8c. KE = GPE KE = 10m x 1N = 10J 8d. KE = GPE KE = .1N x 100m = 10J 8e. KE = GPE KE = 100N x .1N = 10J

9. W = F x d W = 50N x 43m W = 2150J

10. KE = .5mv^2 KE = .5(62)(8.2)^2 KE = 2084.44J

11a. f = ma 30N = 5kg(a) a = 6m/s^2

11b. W = F * d W = 30N * 18.75m W = 562.5J

12a. W = F * d 40000J = 3200N * d  12.5m = d

12b. F = ma 3200 = 1200a 2.67m/s^2 = a

13. KE = W .5mv^2 = W  .5(.150)(40)^2 = W  120J = W

14. W = KE F * d = .5mv^2 417N * d = .5(64kg)(15)^2 17.3m = d

15.

(left or right) Position (up or down) || Elastic Potential Energy || Gravitational Potential Energy || Kinetic Energy ||
 * Energy
 * running || 0 || 0 || 1000J ||
 * full bend of pole while on ground || 900J || 0 || 100J ||
 * peak height || 0 || 1000J || 0 ||
 * landing || 0 || 150J || 850J ||
 * collapsing on cushion || 0 || 50J || 0 ||

16.

Position (up or down) || Elastic Potential Energy || Gravitational Potential Energy || Kinetic Energy ||
 * Energy (left or right)
 * peak height || 0 || 1000 || 0 ||
 * upon landing on the trampoline || 0 || 200 || 800 ||
 * lowest point of the trampoline || 1000 || 0 || 0 ||

17.


 * || Kinetic Energy || Gravitational Potential Energy || Elastic Potential Energy || Sum ||
 * Top of motion || 0 || 1000J || 0 || 1000J ||
 * middle || 500J || 500J || 0 || 1000J ||
 * bottom || 1000J || 0 || 0 || 1000J ||

What Do You Think Now
World class athletes do not defy gravity in any way. some athletes might be able to stay in the air longer than others because they have more leg muscle. This lets them push off of the ground harder, resulting in a higher jump with a longer hang time. Some skaters can do triple axles because they have more muscle to push off of the ground with, resulting in that higher jump with more hang time.