Ch2_OringerP

Chapter 2- Perri Oringer

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Section 1
[] Physicist Writes a Better Formula to Predict Baseball Success Iowa State University physicist, Kerry Whisnant, studied the neutrino, or elementary particle that passes through ordinary matter such as baseballs and baseball bats. He is a St. Louis Cardinals fan and studies the science of the game. He recently changed an old formula written by Bill James that is uses the number of runs scored per game (RPG) and runs given up per game to calculate a team's winning percentage. Whisnant wanted to add run production, consistent run scores, slugging percentage, and varying scores into the formula. His new formula: W1/L1 = (RPG1/RPG2)^a (SLG1/SLG2)^b. He has concluded that: "The more consistent a team is in scoring runs, game to game, the better the team's winning percentage for the total number of runs scored. Runs alone don't tell the whole story. Consistency is another factor. You want to score runs, and you want to be consistent." Whisnant's dream job would be as a part-time analyst for the Cardinals.

What do you think? How do figure skaters keep moving across the ice at high speeds for long times while seeming to expend no effort? Once they start moving at a certain speed/momentum they will continue to. There is nothing their their way or friction from the ground that is stopping the skater from going with no effort. Why does a soccer ball continue to roll across the field after it had been kicked? The kicker put a lot of force on it and it will continue to move at the speed of the kicker plus some more.

Investigate Hypothesis: The steeper the ramp, the higher you will go on the opposite side. The ramp makes a parabola, so the initial height is valuable in determining the maximum height on the opposite side. 1. initial height: 7 m 1e. vertical height of the highest point on the opposite side: 7 m 2a. His maximum height will be about the same because the initial height is the same. Even though the opposite vertical track is not as steep in slope, it will still travel up 7 m because that is the initial height. 2b. I think so because when the skater started at 7m, he went to 7m, therefore, he will stop at or around 7m and not have enough speed/momentum to keep him going 3. My prediction was close for the reason I explained above. 3b. The height in which you start will be the highest point in which you will change direction. (7m again) 4a. With an even less steep slope, his height will remain the same still. 4b. My prediction is the same as the outcome. 5a. No, there is no slope to reach a maximum height (direction changer) 5b. As far as the force/momentum will take it until an unbalanced force comes in contact 5c. momentum would keep the ball on the track 5d. The skater rolled off t he ramp 6a. the length is increasing 6b. It will remain equal to the initial height 6c. the heights are always equal 6d. the skater will keep going until another force acts on it Conclusion: the skater/ball/object will always try to recover its initial height

Physics Talk Newton's First Law of Motion Galileo's Law of Inertia **Galileo Galilei**: observed that a ball that rolled down on ramp seemed to seek the same height when it rolled up another ramp thought experiment: he imagined a ball made of really hard material set into motion on a horizontal, smooth surface. He concluded that the ball would continue its motion on the horizontal surface with constant speed along a straight line "to the horizon" (forever). An object remains at rest unless something causes it to movie **inertia**: the natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line Moving objects may continue to move forever unless a force, push or pull, stopped them Objects do not stop on their own but stop because there is a frictional force that is unseen and stops the object Newton used Galileo's law of inertia **Newton's first law of motion**: 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 **mass**: the amount of matter in an object, or tendency to resist a change in motion If two objects with different masses are moving at the same speed, the one with the greatest mass has the greatest inertia SPEED is NOT important when determining inertia RUNNING STARTS **speed**: the change in distance per unit of time **velocity**: speed in a given direction **acceleration**: the change in velocity per unit of time speed of javelin is the sum of each of the speeds: hand, elbow, shoulder, body FRAMES OF REFERANCE if you run with a ball prior to throwing it, the ball gets your speed before you even try to release it If you can run at 5m/s then the ball will get the additional speed of 5m/s (ball's speed is the sum of your speed b4 release, and the speed of the release relative to your body) **frame of reference**: a vantage point with respect to which position and motion may be described speed is always relative to something if your frame of reference is the moving train, then more thought is required to figure out the pseeds measured by people on the train and by people on the platform if the running start is not permitted, the athlete tries to move every part of his or her body to get the greatest speed

Class Notes: Inertia is a PROPERTY of matter that measures the resistance to changes in a object's motion MASS is how we measure inertia --> __kilogram__ is the base unit in physics weight- how much gravity is pulling on mass Galileo rolled a ball down ramp and notices that the height of the starting point was always the same as the point opposite vertical point that it changes direction. If it starts at a high point and rolls down to a horizontal line (0 slope), the ball will roll forever Running start: beneficial because it takes the speed of your body running plus the speed you are throwing it at if you are in a car at 50 mph and you drop an apple out, it will go 50 mph velocity and speed: velocity has to do with direction acceleration: how fast your speed is changing frame of reference: the perspective you can describe motion from

Checking Up 1. inertia: property of matter that measures the resistance to changes in an object's motion 2. Newton's first law of motion: 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 things will not change their motion unless forced to do so 3. A force is needed to act on an object to stop it from moving at a constant speed 4. What stops the motion of a ball? a frictional force working that you cannot see that stops the object. 5. Of the two, the one with the greater mass will have the greater interia 6. A frame of reference is important because you need a perspective or a "relative." It is the respect to which position and motion may be described. ground, train, yourself, etc.

Physics To Go 1,2,3,4,10 1a. the ball will roll forever unless an unbalanced force comes into contact 1b. Newton's first law of motion: an object already in motion remains in motion with constant speed in a straight-line path 2. It will reach a vertical height of 20 cm again. 3. I don't think that it would be possible to have an object move in a straight line forever because there are obstacles EVERYWHERE. There are changes in surface and also, air in general can be the force that stops an object in motion. Everything has a little bit of friction. 4. The puck moves or "glides" across the ice. It keeps moving in a straight line until it hits the stick (the unbalanced force stopping the motion). Players will purposely have the puck hit the wall so it will reflect and go into a different straight motion. 5. The nearby person sees it go by at 7 m/s (2.5+4.5) 6. The javelin relative to the ground is 14.5 m/s (10.3+4.2) 7a. relative to the ground: 8 m/s forward (5.6+2.4) 7b. relative to the tracks when pushed towards the rear: 3.2 m/s forward (5.6-2.4) 7c. velocity relative to the ground when you and your friend push the cart perpendicular to the aisle as the train moves forward? 6.1 m/s at 67 degrees from cars direction (Pythagorean theorem: v = square rt of 5.6^2 + 2.4^2) (inverse sohcahtoa) 8. The arrow left the bow at 67 m/s 9a. sin45 x d = 15 cm; d= 21.2 cm 9b. sin20 x d = 15 cm; d= 43.9 cm 9c. sin15 x d = 15 cm; d= 58 cm 9d. sin5 x d = 15 cm; d= 172 cm 10a. Newton's First law in 3 sports: -hockey: the puck if not touched will stay at rest and will continue to do so unless a force is acted upon it. When it is hit, it will stay in a straight line motion until it comes in contact with another force (stick). -soccer: the ball if not touched will stay still at rest. When it is kicked, it will go in a straight line constantly until it is stopped by the goal or another player. -crochet: the ball if not hit will remain at rest. It will move in a straight motion forever until it is stopped by a bat or a post 10b. Sportscaster style: -hockey: The puck is at rest and just staying where it is until Mitchell hits the puck and it travels in a straight line until it hits the wall, reflects off, and goes in a straight line in a certain direction. It keeps going until is slides straight into the goal, which stops the puck -soccer: Lucas kicks the ball with a running start so it goes even faster, to beat out the players and go straight in the goal. Unfortunately the goalie stopped it and the ball is staying still at rest on the grass. -crochet: Julianne just lightly hit the ball with her bat though the post. It was going straight through, but a little of the post hit it and the ball stopped without going through. Now the ball is just resting.

What do you think now? 1. Figure skaters can keep moving across the ice for long times because there is basically no friction that can stop them. They are going in straight paths without unbalanced forces stopping their motion. 2. A soccer ball continues to roll across the field because object already in motion remains in motion with constant speed. (Newton's 1st law) The ice skater's speed is determined by his/her body that got a skating start. That speed + the speed she pushed off on. The soccer ball's speed is determined by the speed of the person who got the running start + the speed he/she kicked the ball. they keep moving due to the reasoning of newton's law and they are not coming in contact with an unbalanced force.

Inquiring Further

Curling and Newton’s first law 1. Find out about a sport called curling. It is an Olympic competition that involves some of the oldest Olympians. How can this sport be used to illustrate Newton’s first law of motion?

- Curling shows Newton's first Law of Motion because an unbalanced force causes the stone to increase in velocity from a state of rest.The stone will continue at a constant speed and direction until an external force of friction acts on it.

-a player pushes the stone down the ice to knock a stone out of the house. When the stone that is hitting the other stone it hits it knocking the other stone out of the house and then stops as it hits the stone and stays in the house giving the scoring team a point. the stone moves in a straight-line continual motion until it is stoned by another stone. - []

Section 2
Three sports where there is motion with constant speed -Soccer: the ball is kicked and it travels at a constant speed -Crochet: the ball is hit and travels at a constant speed -hockey: the puck is slapped and travels at a constant speed

What Do You See? I see a boy walking behind a dog and snail and they are all walking at a slow constant speed In the other picture there is a boy running at a faster constant speed and a dog running at a constant speed. The constant speed of the boy is faster than the dog, so he may pass it.

What Do You Think? 100 mi/h and 45 m/s are the speed of the baseball from when it is thrown to when it is caught. Those speeds are from the windup of the pitcher and the speed in which he throws the ball.

Physics Talk acceleration: a change in the velocity of an object over time a = change in velocity / time interval -measured in (m/s)/s speed is a ration of distance traveled to the time taken average speed: the distance traveled divided by the time it took to travel that distance the rate of a change in distance Vav = delta d / delta t - measured in *m/s* instantaneous speed: the speed measured during an instant: the speed as the time interval approaches, but not become zero - negative acceleration during negative velocity-->you are increasing speed - when signs of v & a are the same, it is increasing speed - when the signs of v & a are opposite, it is decreasing speed

 Checking Up 1a. constant speed: the distances between ticks were equal length 1b. positive acceleration: when gradually increasing the speed, the distances between the dots gradually got longer 1c. negative acceleration: when gradually decreasing speed, the distances between the dots gradually got shorter 2. Vav = change in d / change in t; Vav = 400m / 50s; Vav = 8 m/s 3. instantaneous speed: the speed of a **single** instant average speed: the average speed of **several** instances 4. vf = vi + at CHANGE TO M/S^2 2.8 m/s/s

Physics To Go

1. Instantaneous speed is the speed a single instant, or second. Average speed is the average of several speeds, instances. 2a. Vav = d/ t ; 1000m/15s ; Vav = 66.67 m/s 2b. Vav = d/ t ; 84m/6s ; 14 m/s 2c. Vav = d/ t ; 9.6 km/ 2 hr; 4.8 km/h 2d. Vav = d/ t ; 400km/4.5h; 88.89 km/h 3a. negative acceleration (slowing down) 3b. positive acceleration (speeding up) 3c. no acceleration 3d. negative acceleration 3e. no acceleration 3f. no acceleration 4a. graph with a constant increase in speed: a, d 4b. graph with a constant speed: b 4c. graph with a greatest change in speed: a 4d. graph with an increase then a decrease: c 4e. acceleration of student a: positive student b: no acceleration student c: increasing and then decreasing (positive then negative) student d: positive acceleration 6. -1.4 (m/s)/s --- WORK IS ABOVE for the following problems 6a. it has a negative value 7a. constant speed 7b. increasing speed 7c. slow constant, increasing, faster constant, decreasing, slow constant 7d. decreasing, constant, increasing 8. 50 mi/h 9. No, if the average speed was 15 m/s, the instantaneous speed is not always 15 m/s. The average takes the final speed and the initial speed and averages them, which might be 15. The instantaneous takes one speed, so it may be 15 or it could be 12. 10.x.x..x......x.........x...........x.............x .............x.............x 11. The car is 20 m/s more after every 5 s. 14. sports with similar ticker-tape patterns a. constant at an average speed: soccer when the ball is kicked b. constant at a fast speed: race car driving c. constant at a slow speed: golf when close to the hole d. positive acceleration: long distance running: start slow and then quickly increase speed at the end e. negative acceleration: back stroke in swimming

Physics Plus ball towards the wall --(5m/s)--> ball rebounds the wall <--(5m/s)-- 1. a=Vf-Vi / t ; a = -5m/s - 5m/s / 1s = -10 m/s^2 Why is it bad to make car bumpers out of rubber? The car would bounce off with the same speed backwards, and the increase acceleration of bumping will damage the body. A bumper that crushes will make the time longer that it would bounce off. The rubber would decrease the time of bumping off, increasing the acceleration of the rebound. -Rebounding: change in direction -Even if Speeds are small, accelerations can be huge if the bounce times are tiny. 2. a=Vf-Vi / t ; a=-0.5m/s - 0.5m/s / .20s = -5 m/s^2 acceleration for the entire time 3. all answers are -5 m/s^2
 * velocity || acceleration || example ||
 * small || small || turtle ||
 * big || big || race car, airplane, rocket ||
 * small || big || deer, dog, *rebounding* (any object) ||
 * big || small || truck ||

What do you think now? 100 mi/h and 45 m/s are both average speeds or instantaneous speeds. They are measurements of velocity, being that they measure distance in relation to time. You could find velocity by dividing distance traveled by elapsed time.

Section 3
What do you see? I see a person walking with a stick pushing a ball that is right on the stick. He is going at a slow speed. The person then starts to run trying to move the ball from the bottom of the stick but it is still moving right in front of it. The person then moves even faster and the ball is still pushing up on the stick.

What do you think? 1. a force is a push or a pull 2. the same amount of force will much move (push/pull) the tennis ball with more ease because it has a much lower mass.

Physics Talk & Checking Up Equation for Newton's Second Law of Motion Acceleration = force / mass a : (m/s)/s f: N m: kg a=F/m ; F=ma ; m=F/a Where There's Acceleration, There Must Be an Unbalanced Force -2nd law: Accelerations are caused by unbalanced forces -if you observe an acceleration (change in velocity), then there is a unbalanced force causing the acceleration -a force to an object with a small mass, the acceleration is large -a force to an object with a large mass, the scceleration will be smaller -acceleration gets less and less as the mass gets larger and larger -even when it seems acceleration is zero, that is not true bc Newton's law is always valid -acceleration of an object is directly proportional to the applied force and inversely proportional to the mass Sample Prob : As the result of a serve, a tennis ball (mt = 58 g) accelerates at 430 m/s^2 for the very bried time it is in contact with the racket F = mt(a) = (.058)(430) = 25 N Significant Figures -zero between nonzero digits - yes -zero at the end of a decimal number - yes -zero at the beginning of a decimal - no -large number w/o a decimal point - no Gravity, Mass, Weight, and Newton's Second Law weight: the vertical donward force exerted on a mass as a result of gravity equation: Fgravity = (m)(Agravity) ; W = mg m = kg ; g = acceleration due to gravity Balanced and Unbalanced Forces -when two forced act at the same time, the direction as well as the magnitude of the forces determine the motion of the object -the the forces are in the same dirction, then the sum of the forced or net forcecould be zero and there would be zero acceleration -free-body diagram: a diagram showing the forcs acting on an object -when you hold an object in your hand, it does not move or accelerate downward. There is the force of your hand pushing up on the object UP: force of hand on apple DOWN: force of gravity on apple -car on highway: force of the road on the tires moving it forward. force of air resistance is applied against the vehicle  (car)

Checking Up 1. Newton's Second Law of Motion: an object will accelerate if it is pushed or pulled on  2. increasing an object's mass and with a force acts on it, the acceleration will be smaller 3. If an object weighs 30 N. Weight is the vertical donward force exerted on a mass as a result of gravity. The force therefore is 30 N. 4. On a planet with a higher acceleration, your weight would increase, but your mass would remain the same.

PTG 1. a.350N, b. 80 kg, c. 10 m/s^2, d. 80 kg, e. -15 m/s^2, f. -3000N 3. F = (m)(a) ; 42N = (.30kg)(a); a = 140 (m/s)/s 4. F = (m)(a) ; F = (.040kg)(20m/s^2) ; F = .8N 5a. Newton's first law of motion: a bowling ball had a larger mass than a baseball. Therefore it has more inertia. A greater force than a human would need to throw the bowling ball fast enough so it continues at fast speed. The baseball has less inertia but will travel in straight-line motion for longer and with greater force because it easier to for the force of our bodies to accelerate it.

the more mass- the more inertia - the harder it is to start/stop moving

5b. Newton's second law of motion: In the equation F=ma. Mass and acceleration are indirectly proportional. So, a baseball with less mass will have a greater acceleration than a bowling ball with a larger mass. Therefore, it is going faster when it hits your hand, so it will hurt. The bowling ball will go slower (less of an acceleration). more force on the bowling ball to achieve the acceleration of the baseball 9. When you throw a ball, the force of your hand is acting upon the ball until an unbalanced force comes in contact with it.

10. 50N + 40N = 90N 11. 4 adults x 200N each = 800N 12. F=am; 125N =a(.7kg); 179 m/s^2 13. Resultant Force: 130N north @ 67 degrees NE 14. Resultant Force: 6403N @ 39 degrees 15. F=mg ; F=(12.8kg)(9.8m/s^2) F= 125 N 16a. 50N @ 53 degrees 16b. f=ma; 8.9 m/s^2 17a. 36N @ 34 degrees 17b. f=ma; 36=100a 0.36 m/s^2 17c. 50N = 100kga a= .5 m/s^2 18. Sports announcer: A tennis ball of .057kg was just served at and accelerates at 430 m/s^2. That great serve was made with the server's swinging and body force of 24.51N. RACKET put the force on the ball.

WORK for physics plus & PTG

Physics Plus 1. 125 NW @ 45 degrees a. resultant force: 0N b. 81 N c. direction of net force: NW

What do you think now? Force is a push or a pull Mass and acceleration are indirectly proportional. So with, the same force, the bowling ball, which has more mass, would have a lesser acceleration. The baseball, with a smaller mass, would have a greater acceleration.

Section 4
What do you see? There is apples being dropped straight down and thrown the the right. A boy is timing both directions. The apples are even in a horizontal line.

What do you think? What determines how far an object thrown in to the air travels before landing? the force you put on it, the angle you throw it at, the weight of the object, the speed it has, acceleration

Investigate Part C 1. As the horizontal launch velocity increased, the hang time remained the same. 2. As the launch velocity increased, the range increased 3. As the initial height increased, the time in the air increased 4. As the initial heigh increased, the range increased 5. Factors that influence the time of flight: initial height 6. Factors that influence the range: initial height and the initial speed

Physics Talk projectile: an object acted on ONLY by gravity x component and y component of all vectors are independent -vertical velocity affects vertical motions and horizontal velocities affects horizontal motions -y is VERTICAL and x is HORIZONTAL Time for a horizontally launched projectile to reach the ground (hang time) is the same as the time it takes to drop. Acceleration due to gravity is -9.8 m/s^2 Vertical velocity changes by -10 m/s every second. Horizontal velocity **doesn't** ever change Vy = 0 at maximum height throwing horizontally results in the same trajectory (path) as the second half of the path of a ball thrown at an angle Checking Up

1. If a pen and ruler are dropped together from the same height, with reach the ground at the same time because there is no air resistance. 2. When an object falls vertically down, it doesn't remain the same because vertical velocity is constantly changing. (speeding up 10m/s) 3. If a ball is thrown upward the ball's velocity at its highest point is 0. The acceleration is 9.8 m/s/s

PTG 1. X........... X X.................X  X......................X  X .........................X

2.

X.........................X X................................X  X......................................X  X ..........................................X

4. They believe that a bullet that is dropped and one that shot horizontally will arrive at the ground at different times because they believe that the velocity will keep it in the air longer. Really they will hit the ground at the same time, the vertical velocity is the same, but the horizontal velocity is different. The time only depends on gravity (which is the same) and distance. 6. A projectile's horizontal motion has no effect on its vertical motion, and vice versa. Vertical velocity changes by -10 m/s every second. Horizontal velocity does not change ever. Vertical changes, and Horizontal does not. We see that by the stair case way of drawing the curve. Constant speed for X, and increasing speed down.

7. Both arrows will take the same time to strike the horizontal plane.

8. 3.6 m/s @ 33.7 degrees 9a. 11.98 m/s 9b. 23.96 m 10a. 8.5 m/s 10b. 4.25 m 11. The pitcher has just thrown the baseball at a 25 degree angle above the horizontal at a velocity of 80 m/s from the ground. Horizontally, it has no acceleration, but vertically it has an acceleration of -9.8 m/s/s. The time it takes to reach the batter was just 3 seconds! After these three seconds, the ball was traveling at 72.5 m/s... That's fast!

Physics Plus

Video Clip & Questions

[] [|www.youtube.com/?v=qo5PfhlzDCo]

1. Projectile motion occurs when a basketball is thrown while making a jump shot. Change only occurs in the vertical direction. As the ball goes up, it looses velocity, but when it reaches 0 m/s^2, the ball comes down and speeds up into the hoop. With no air resistance there is no horizontal change, so it will continue to move in the direction that the person was moving, or their arms were. Horizontal- how far forward the b-ball is going to travel. Vertical- how high up 2. The shape of the trajectory is important because then you can see the parabolic path the basketball takes. When you shoot a shot, the ball continues forward while going up and then down. Vertical position vs. horizontal is a parabola. Horizontal motion is constant, while vertical motion is uniformly accelerated.

What do you think now? What determines how far an object thrown into the air travels before landing? launch velocity What do you think determines how far an object travels after it is thrown? initial height and the initial speed

Section 5
What do You See? I see a ball being kicked up, and then falling down, bouncing off a boy's head and going up & then down again. What do you think? 1. smaller angles have long ranges velocities and are up for a shorter amount of time larger angles have smaller rangers and are up for longer amount of time 2. The greater the speed, the faster (covering more distance) the object will travel, so the range will be longer.

Physics Talk Modeling Projectile Motion Projectile has two motions that act at the same time and do not affect one another -One motion is constant along a straight line (affected by launch speed and direction -second is downward acceleration at 9.8 m/s/s. (affected by launch)  Mathematical Model: table of times, speeds, and distances during falling  Physical model: the evenly spaced strings of calculated lengths  Without air resistance, all trajectories are parabolas  DiagramL trajectories launched at different angles but with the same speed  all balls travel in parabolas  -a 45 degree launch produces the greatest range (longest distance)  -pairs of angles (add up to 90) are identical distances  small angles have greater horizontal velocities but are up for a shorter amount of time  large angles have smaller horizontal velocities but are up for longer amount of time  Exceptions: curve balls, temperature

Checking Up 1. Two types of motion: constant motion and downward acceleration 2. For a model to be accepted, it must match reality in nature 3. Height and range with different angles: a 45 degree launch produces the greatest range (longest distance), -pairs of angles (add up to 90) are identical distances

PTG

1.) 45 degrees because the object will go the farthest it can. 2a.) When bigger than 45 degree angle, the less far the object will go, the **more** time you will spend in the air. 2b.) As the angle gets bigger before it hits 45 degrees, the object will go farther, but the smaller the angle, the **less** amount of time in the air. 3a.) 90 degrees- 30 degrees = 60 degrees 3b.) 90 degrees- 15 degrees= 75 degrees 4.) It is a human error because it is physically impossible to launch yourself at a 45 degree angle. most people can run faster horizontally, than they can jump high up. 5.) He was probably good at the long jump because he could probably jump high. Also, he used his speed to get a running start and have longer time in the air, covering more distance. His Horizontal velocity is fast and his Vertical height is high. 6a.) a=-g=-9.8m/s^2 down. 6b.) V max = Vix only because Vy = 0 at max height

7a. vertical speed final: 29.4 m/s 7b. horizontal speed @ 1s: 5.0 m/s 7c. distance from cliff: 15 m 8. 45 degrees or close to it would give it the longest range 9. The angle that produces the greatest projectile height would be the one closest to 90 degrees 10a. the direction of acceleration is down 10b. seconds to reach ground: 4.5 s (ignore work above for this problem. correct work: -100 = .5(-9.8)t^2 ; t = 4.5 s 10c. distance from cliff: 90 m (correct work: dx = VixT ; =(20)(4.5) ; d = 90 m

Physics Plus

What do you think now? A 45 degree angle gives the longest range. Anything bigger gives you more time in the air but a shorter range. Any two complementary angles (15&75; 20&70) give you the same range. a greater launch speed of a projectile might change the range when the launch angle is the same because if it is launched faster it is going to go farther.

Section 6
What do you see? I see a person on a chair with wheels with his feet on the wall. He pushes off the wall and flies back fast with the chair on the floor and his body still in the chair.

What do you think? If I were to instruct someone to jump, I would start with having them plant their feet. Then they would have to bend their knees. After, they would have to go on the balls of their feet and straighten their legs again. The force would be normal going up, weight, when standing and bending. You are applying a gravitational force.

Physics Talk Newton's Third Law of Motion: -for every applied force, there is an equal and opposite force. The two forces always act on different objects -Forces are always equal in the opposite direction -forces come in equal and opposite pairs -push on the wall and the wall pushes back with the SAME force and you can't make the forces unequal Inanimate Objects can Push Back: -objects can apply force due to mass and gravity. -free body diagram: a diagram showing the forces acting on an object -when standing, your mass is pulling you down. If not for an equal force from the floor that was going up, you would fall down. Challenging Newton's Third Law how something/someone can Pull something/someone ex: person on wheely chair person pulls on chair w/ small force. The chair pulls back on person with equal small force. The one force on the chair makes it move forward. Two forces on the person--one of the ground and other of chair, which are not equal. Ground force is larger making the person move forward

Class Notes- Newton's Laws of Motion 1.) an object at rest will stay at rest, and an object in motion will stay in motion at constant speed in a straight line, unless an unbalanced force acts on it 2.) Acceleration is directly proportional to net force and inversely proportional to the mass of the system; F = m x a 3.) every action has an equal but opposite reaction -all forces come in pairs but act on two different systems ex: person pushing a box. FORCE ON PERSON: The force of the box on the person, the ground pushing up, force of gravity of the Earth on person FORCE ON BOX: force of ground on box, force of gravity of earth, force of person on box FORCE ON GROUND: normal force of person and box pushing down ex: earth and moon. Why does moon go around earth. Force of earth on the moon pulls it in. The moon must pull on the Earth will equal and opposite force. The moon has enough mass to get water to shift - tides. When standing on Earth, we are pulling it up Fg and pushing it down. When we fall, we are still pulling the earth up, but the mass of Earth is so much bigger than us that we cannot feel it. Forces are same, but when one of the masses is bigger, the acceleration of that object is smaller m(down) x a(up) = m(up) x a(down)

Checking Up 1. Newton's 3rd law of motion: if you push or pull on something, it will push/pull back with equal force in the opposite direction. Forces come in pairs and act on different objects. 2. Earth pulls down a mass with a force of gravity. The mass pulls up on the Earth with an equal force of gravity. 3. A free-body diagram shows the forces acting on an object.

PTG

1.) Yes. This is because every action has an equal but opposite reaction. 2.) No, there is no deflection. There are springs. And when your weight or force you are putting down is the max it can hold, the spring goes up. The chair compresses. "Restoring" forces balance downward weight. 3.) Spring with needle attached. Calibrated. It reads your normal force pushing down and the scale pushing up on you. They are two different systems with an equal force. You are really reading with the scale is doing to you. Nscale on you - W = ma 4.) The material of the bat can not withstand the great force of the ball. Fball is too big for material to withstand. 5.) Equal but opposite force. The smaller player has bigger acceleration, but smaller mass. 6.) Normal force of person on boards and boards on person. There is no friction because of the ice. 7.) Baseball players perfer to wear gloves when catching a ball because all forces come in pairs so when the ball hits the players glove, his hand is going to need to exert the same force on the ball. Padding causes lower acceleration which reduces force on hand. 8a.) WOW! The player just slammed into the boards. He exerted a large force on the boards going at a high acceleration. The boards exerted the same force, but has a larger mass which made the player stumble a little. But, the force of the player's weight was strong enough to keep him on the ground. There was no friction because hockey is on ice, which is too slippery! 8b.) A deflection of the ground can produce a force if you were to fall. During the fall, you would be pulling up the force from the ground while pushing down the force of your own. I would make this more exciting by showing a clip of a soccer player tripping, and falling and commenting on it with enthusiasm.

What do you think now? When you jump you apply a gravitational force downward and a normal force goes through the body upward. Because we push down on the floor with a force, due to Newton's third law, the floor must have an equal and opposite force upward on us.

Section 7
What do you see? It looks much easier to move on the ice and pull the shoe, but on the same, it is harder for her to pull the shoe in the sand

What do you think? 1. Some sports require special shoes because they are sports that have certain activities where you need to jump, remain on the ground, or pivot a lot. The motions all vary. 2. The features that vary in shoes for different sports are: springs, thickness of bottom, smoothness, spikes, laces, material.

when friction is bigger than tension, you slow down when tension is bigger than friction, you speed up tension = friction normal = weight coefficient of friction has NO UNITS coefficient of friction: the higher the CoF, the rougher the surface wax is used to create more friction for icy surfaces, but for surfing you put it on for feet to stick

Physics Talk Friction **Analyzing the Forces Acting on the Shoe** -friction: a force that resists relative motion between two bodies in contact -2nd law: vertical forces on the shoe must add up to zero The downward force of gravity on the shoe must be the same as the upward force applied to the shoe by the surface normal force: the force acting perpendicularly or at right angles to a surface (equal in force and ipposite in direction to the shoe's weight) ** ^floordown gravity** coefficient of sliding friction: a dimensionless quantity; its value depends on the properties of the two surfaces in contact and is used to calculate the force of friction -the force of friction is = force required to slide the oject on the surface with a constant speed **coefficient of sliding friction = Ffriction / Fnormal** -no units bc it is a force divided by a force -expressed in decimals -valid only for the pair of surfaces in contact when the value is measure -if a surgace were tilted or if the pulling force were angled up/down, the force exerted by the surface on the object would be harder to determine

Checking Up

1. The force of friction is equal to the force reading on the spring scale because the pulling force applied was equal to the frictional force, and since the two forces were in opposite directions, the net or total force due to them was zero 2. coefficient of sliding friction has no units because it is a force divided by a force 3. the force of friction is = force required to slide the object on the surface with a constant speed

PTG 1. You were cleats, which have things that stick out into the ground to keep you from slipping. Those spikes make fore high traction 2. In skiing, skiers wax skis and in ice skating, skaters sharpen their skates. 3. No, she will not know if her shoes will provide the same amount of friction on a court outside of her home. She needs to know the material of court, the roughness, and how it will react with your sneakers. 4. Tennis players have different shoes for clay, grass, and hand surfaces. For the hard surfaces, their shoes need to provide more friction. On the clay courts, which are more slippery, the shoes need to provide more friction & have a good grip. For grass, the shoes need to provide less friction. 5. F=ma. N = w = 600 N ; mu=f/n .03 = __ / 600 N. The minimum horizontal force would have to be 18 N to keep the skier coasting at constant speed across level snow.

6a. W=mg ; W=(1000)(9.8) ; W=9800 N 6b. mu=f/N ; .55=f/9800 ; f=5390 N 6c. Fx=MAx ; f=ma ; -5390=1000a ; a= -5.39 (m/s)/s 6d. Vf=Vi+at ; 0=Vi+(-5.39)(6) ; Vi = 32.34. Change in speed: 32.34 m/s 6e. Original speed: 32.34 m/s. The driver's claim was wrong. He was going faster than he should have been driving: 32.34 m/s and he said he was driving 29m/s. If the speed limit was 65 mi/hr, he would get a ticket

7. As you are going faster and faster, there is more and more air resistance. If you try to run through the water, it gets harder and harder to do. The resistance picks up as the speed picks up. When I am running and increasing speed, the same wind resistance is hitting my face. Air and water resistance depend on speed. 8. If there is a max. force it will set a limit on how fast you can start. Even if you have incredibly strong legs, it won't have more acceleration. To solve this problem, we can reduce friction by buying shoes that have a smoother surfaces. fkMax limites acceleration 10. Friction is important to running, baseball, soccer, and other sports. Cleats are used because you need friction to keep the players "sure-footed" and dug into the ground. Friction- you can put more force on the ground without slipping. We wouldn't be able to walk without friction. 11. We are here at the basketball game and the players are wearing new shoes. They claim that the shoes are a little heavier so there is more friction, to keep them grounded. In basketball, players can't slip around the court and need to be sure-footed. These shoes will running around the court, exert a force in the direction the player is running, it also provides the force of gravity, and a normal force up from the ground. Good luck players!

Physics Plus 1.)

Lab: Bowling with Blocks

1. The coefficient of friction in Part I displays the force necessary to move the block divided by the pressure of the floor on it. Also, it displays the friction/forces against each other between the block and the floor. 2. My mu was .28 and the class mu was .33. The percent difference is 15.2%. The results do not have to be the same because of random errors or systematic errors. 3. My times were sort of comparable. They were all lower than the actual calculated times. My percent error was too high. Highest: 24.9% and Lowest: 18.9%. 4. Although my percent error was too high to get a sense of reality, the theoretical physics we are doing in class applies to the real world because most sports we play display this Neweton law. Bowling for example, contains the coefficient of friction. 5. 3 sources of experimental error: if the tape measurer was on a slant, the distance could be thrown off. If the the floor has bumps, it can throw off the acceleration. Finally, if the stop watch was not stopped/started quick enough, the calculations for part II would have errors. Also, if you threw the block and it bounced. Class Data: Part I N || Mu || Class Avg. Mu || % Difference || Part II Fx = max ; f=max ; .46=.17a ; 2.7(m/s)/s=a Fy = may ; N-W=0 ; N=W ; W=(.17)(9.8) ; W=1.66N Mu=f/N ; .28 = f/1.66 ; f=.46N Vf^2 = Vi^2 +2ad ; -Vi^2 = -24.84 ; 0=Vi^2+2(-2.7)(4.6) ; Vi = 5.0 (repeat for 3 trials) Vf = Vi + at ; 0 = 5 + 2(-2.7)t ; t=1.85. (repeat for 2 other trials) For all errors: (calculated time-measured time / calculated time) x 100
 * Tension N || Tension N || Tension || NFf(N) || Total Weight
 * 3.3 || 3.4 || 3.3 || 3.3 || 11.8 || .28 || .33 || 15.2 ||
 * Mass (g) || Mass (kg) || Measured Time (s) || Measured Distance (m) || Ff (N) || Acceleration (m/s)/s || Calculated Vi (m/s) || Calculated time (s) || % error ||
 * 170 || .17 || 1.39 || 4.6 || .46 || -2.7 || 5.0 || 1.85 || 24.9 ||
 * 170 || .17 || 1.71 || 6.11 || .46 || -2.7 || 5.7 || 2.11 || 18.9 ||
 * 170 || .17 || 1.27 || 3.71 || .46 || -2.7 || 4.48 || 1.66 || 23.5 ||

What do you think now? -Some sports require special shoes because of different weather conditions and material of the surface the game is played on. For example, a basketball player needs shoes with good traction because the surface would be slippery of there was not enough mass and gravity on it. -Different features of shoes are useful for different sports You were cleats, which have things that stick out into the ground to keep you from slipping. Those spikes make for high traction. If you were playing in the grass, you might wear a shoe that is smoother and less mass, so it is easy to move/accelerate. Otherwise, the coefficient of sliding fricition would be too high (µ=friction/normal). the force of friction is = force required to slide the oject on the surface with a constant speed

Section 8
What do you see? There are pole vaulters who are running (accelerating), moving with momentum, putting the pole down, the pole bends, and the vaulter hangs on until he is launched into the air over the wall.

What do you think? The vaulter may not be able to go over a 12.0 m high bar with a 11.0 m long pole because they can't accelerate quick enough and go with a constantly increasing momentum that the pole would bring them over the high bar. Factors that limit height of pole vaulter: acceleration, velocity, length of pole, momentum, distance

Investigate Prelab Activity: a. technique: bend the ruler as far as possible and make sure that little of the ruler stick is sticking out so the penny blasts high in the air. b. factors: flexibility, deflection, how much it sticks out, where the penny is placed, how high above ground the ruler is Instructions: deflection 1a. I will be able to conclude how deflection effects the height of the penny. 1b. I will record how high the penny goes and how low the ruler goes when I force it downward. 1c. Tools I will use: meter stick, ruler, penny, tape 1d. I will analyze my data by determining if a greater force (deflection) will make the penny go higher or a lesser force will make the penny go higher. Data Table: (downward dist.) || 1 cm || 2.5 cm || 3.5 cm ||
 * Trial || One || Two || Three ||
 * Force
 * Height of penny || 20 cm || 56 cm || 97 cm ||

Physics Talk Law of Conservation of Energy a force can change the position and speed of an object in a way that allows the position and speed to change back Kinetic energy- energy associated with motion gravitational potential energy- energy an object possesses because of its vertical position from Earth potential energy- energy associated with position SUM of potential and kinetic remains constant Law of Conservation of energy: energy cannot be created or destroyed; it can be transformed from one form to another, but the total amount of energy remains constant Energy and Work while a ball is rising or falling, the sum of gravitational potential and kinetic energy remains constant work- the product of the displacement and the force in the direction of the displacement (physics quantity that equals the force multiplied by the distance) Conservation of Energy in the Pole Vault elastic potential energy- the energy of a spring due to its compression Work = F x d Elastic Potential Energy = 1/2kx^2 Gravitational Potential Energy = mgh Kinetic energy = 1/2mc^2 Joule = 1 N x m = 1 (kg x m^2 / s^2)

Checking Up 1, a force is the reason for energy to change 2. The penny gets its energy from a ruler that has elastic potential energy 3. The vaulter's kinetic energy is used to catapult him with an inital speed upward and the remaining kinetic energy is turned into elastic potential ernergy as the pole bends. 4 Joules is the unit of work or energy

PTG

1. The shot put is launched by hand (work) and is increasing speed (kinetic energy). In the air, while picking up speed & changing speeds, there is kinetic energy. That is turned into gravitational potential energy as the shot put is thrown above its starting position. The ball eventually drops and the ground stops it through work. 2. The golf ball stays at rest and then is hit by a club which is work. The ball travels and increases speed which is kinetic energy. When above its surface, the ball has gravitational energy. On the way down, there is kinetic energy. After, the ground (friction) then causes the ball to stop (work).

3. KE = GPE 1/2mv^2 = mgh 1/2(12)^2 = (9.8)h 7.3 m = h

4. What is really limiting the vaulter's height is his/her speed.

5. The pole would increase temperature as the vaulter does work on the pole with first kinetic and then elastic energy. But at the pule straightens, it will decrease in temperature as the vaulter increases his/her gravitational potential energy

6. KE = GPE 1/2mv^2 = mgh 1/2v^2 = (9.8)(4.55) v = 9.44 m/s

7. KE = GPE 1/2mv^2 = mgh 1/2v^2 = (9.8)6.14 v=10.97 m/s Sergei's speed is higher than Emma's speed.

8a.) GPE = KE mgh = 1/2mv  (9.8)(100) = 1/2v  v = 1960 m/s  8b.) You don't need the mass of the rock because it cancels out

9.) Wpullback = EPEf W = 1/2kx^2  W = 1/2(1500)(.25)^2  W = 46.875  9b.) EPE = KE  1/2kx^2 = 1/2mv^2 1/2(1500)(.25)^2 =1/2(.1)v^2 v=30.6 m/s

10a.) EPE = W 1/2kx^2 = F x d  1/2(315)(.3)^2= W  14.2 = W  10b.) 14.2 = F x .3 47.3 N = F

11.) GPE = EPE mgh = 1/2kx^2  .04(9.8)(1)=1/2(18)x^2  x = .21

12a. F (measured in N)= m(measured in kg) x a(measured in m/s^2). Therefore 1N = 1kg x 1m/s^2 12b. GPE=mgh ; (kg)(m/s^2) ; 1kg x 1 m/s^2 = J 12c. KE=1/2mv^2 ; 1/2(kg)(m/s)^2 ; 1kg x 1 m/s^2 = J 12d. EPE = 1/2kx^2 ; 1/2[(kg)(m/s^2)/m]m^2 cancels out to 1kg x 1 m/s^2 = J, the same way GPE = kx^2 does 13. EPE > KE > GPE > KE

14.) during the push up of the ball is work, that work is turned into kinetic, and then to gravitational.

15. The baseball is initially at rest. It then is hit by the bat, which does work that transforms into kinetic energy as the ball picks up speed in the air. That kinetic energy then transforms into gravitational energy, then back to kinetic, then work is done by the ground to bring it back to rest.

16.) Soccer: the ball is moving at increasing speed, which is kinetic energy, and ball is then kicked up, still traveling with kinetic energy, as it gets to its highest point, the KE transforms into gravitational potential energy. The ball's energy is transformed into work as the net and ground make the ball come to rest.

What do you think now?

You can't just double your height if you double your distance because it is the SPEED that matters, not the length of the pole. It is the speed because the higher the velocity, the higher the kinetic energy, and that means the higher the Gravitational potential energy (height)

Section 9
What do you see? I see a skater jumping for the ground twirling in the air. A person in a helicopter is timing her hang time.

What do you think? The hang time of some athletes does not defy the pull of gravity A world-class figure skater does not defy gravity to remain in the air to spin because he/she built up enough energy (KE, GPE, EPE, and work) to be able to do a triple axis.

Investigate Prelab 1. watch video - skater 2. 20 frames during which the skater was in the air 3. 1/30 = 20/30 = 2/3 of a second in air 4. Frames 8-10 was when the skater appeared to "hang." These frames seems to be all at the same height for a longer amount of time because the change in those positions (displacement) are so small. 1. watch video - bball 2. 31 frames in which the player was in the air 3. 1/30 = 31/30 = about 1 second in air 4. the player was able to look like he was hanging because the top frames had very little displacement in height

1. Sequence of events of a jump: Bent knees >(WORKunbending legs)> unbending knees >(GPEfinal)> airborne ( height off floor) 2. what you need to measure the force needed to jump to a certain height: weight (gravity), height above ground, gravity, knee bend 2a. we will be able to conclude the force of our jump 2b. we will record the max height, our weight in newtons, knee bend. We will use the equation W = GPE and plug in the info looking for F. 2c. tools: meter stick, calculator 2d. We will analyze our data is graph form Force on y axis and time on x axis and comparing it to our calculations

5. Calculation W = GPE F x d = mgh F x .085 = 47.62(9.8)(.24) F = 1317.7 N Measurement: 918.19 N. My calculation is higher, so my actual measurement was lower, so my jump on the scale was accidentally not as high. Percent Error = |calc-exp| / calc x 100 - 30.3% error :(

Physics Talk Conservation of Energy <jump chart in ready position about to jump, you have EPE from contractions in muscles. launch position has both GPE and KE energy of all positions of a jump are equal the greater the peak position, the greater the GPE trampoline potential energy from height jumping would provide kinetic energy when you land. when going down, you continue to have kinetic energy bc you would be losing GPE. The trampoline stretches & gains EPE at the expense of KE and changes in GPE example: all energy can be measured or calculated conservation on energy: total of all energies at any one time must equal the total of all energies at any other time collision between a player's foot and soccer ball, the ball can gain KE and move faster. Whatever the ball gained in energy, your foot lost that energy. No matter what is lost or gained, the total energy remains the same

Checking Up 1. The jumper can move from the ready position to the launch position from the contractions in the leg muscles- EPE 2. in Launch position the student has both GPE and KE. Peak of jump - GPE. 3. three other types of energy: light energy, chemical energy, sound energy

PTG

1. W = GPE W = mgh W = 50(9.8)1 W = 490 J 2. Bobsled run. W > GPE > KE > Wbreak 3. We would go about seeing if the statement is correct by making lines where the player's foot is during each frame. There they will see that the player does not actually hang in the air, but his maximum heights have little displacement therefore it results in people assuming that there is hang time. 4. If someone where to claim that a law of physics can be defied, they should give total proof of their (false) information. Afterwards, someone else who is more knowledgeable and also has run many tests on the subject, can prove that the claim is not true. Therefore, both of them have the burden of proof. Other people will duplicate experiment and try to get same results. 5. An athlete can increase their jump by increasing force by increasing muscle strength or decreasing mass, but not strength. 6. W = F x d a) 1N x 1m = 1J  b) 1N x 10m = 10J c) 10N x 1m = 10J d) .1N x 100m = 10J e) 100N x .1m = 10J 7. W = GPE SAME^  a) 1N x 1m = 1J b) 1N x 10m = 10J c) 10N x 1m = 10J d) .1N x 100m = 10J e) 100N x .1m = 10J 8. KE = GPE SAME^ a) 1N x 1m = 1J b) 1N x 10m = 10J c) 10N x 1m = 10J d) .1N x 100m = 10J e) 100N x .1m = 10J 9. W = F x d  50 x 43  2150 J

10. KE = 1/2mv^2 KE = 1/2(62)(8.2)^2 KE = 2084.4 J 11. a = F / m 30 / f  a = 6 m/s^s 12a. W = F xd 40000 = 3200 x d  d = 12.5 m  11b. W = F x d W = 30 x 18.75 W = 563 J 12a. W = F x d 40000 = 3200 x d  d = 12.5 m  12b. a = F / m 3200 / 12.5 a = 2.7 m/s^2 13. KE = W 1/2mv^2 = W  1/2(.15)(40)^2 = W  W = 120 J  14. W = KE F x d = 1/2mv^2 417d = 1/2(64)(15)^2 d = 17.3 m 15﻿. Pole Vault: workout = 950 J 16. Trampoline: GPE at max. height > KE when about to land on trampoline > EPE when hitting tramp. surface and going back up 17. Skiing: top of the mountain is GPE > during the run is KE > at the bottom is work when stopping
 * || KE || GPE || EPE || SUM ||
 * Running || 1000J || 0 || 0 || 1000 ||
 * Full bend of pole || 100 || 0 || 900 || 1000 ||
 * peak height || 0 || 1000 || 0 || 1000 ||
 * landing || 850 || 150 || 0 || 1000 ||
 * cushion collapse || 0 || 50 || 0 || 0 ||
 * || KE || GPE || EPE || Sum ||
 * peak height || 0 || 1000 || 0 || 1000 ||
 * landing || 800 || 200 || 0 || 1000 ||
 * lowest height || 0 || 0 || 1000 || 1000 ||
 * || KE || GPE || EPE || Sum ||
 * top of mtn || 0 || 1000 || 0 || 1000 ||
 * middle || 500 || 500 || 0 || 1000 ||
 * bottom || 1000 || 0 || 0 || 1000 ||

18. In soccer, the ball is kicked which is work. Then it accelerates which is kinetic energy and is above ground which is gravitational potential energy. On the way down there is also kinetic and gravitational potential energy. At the end, there is friction to stop the ball, which is work

Physics Plus 1a. KE = GPE 1/2mv^2 = mghi = mghf 1/2v^2 = (9.8)(50) = (9.8)(30) v = 19.8 m/s 1b. It is advantageous that the mass is independent because because it cancels out and the rides will fall at the same rate (KE) despite the mass. You want it to work no matter who is on the ride. 2. EPE = KE 1/2kx^2 = 1/2mv^2 1/2(60)(.4)^2 = 1/2(.3)v^2 v = 5.66 m/s 3. GPEi+Win=KEf+GPEf+Wout mgh+F*d=1/2mv^2+mgh+F*d (200)(9.8)(25)+200,000=1/2(200)(40)^2+20(9.8)(h)+50,000 249,000=160,000+1960h+50,000 h=19.9m

What do you think now? The "hang time" of some athletes does not defy the pull of gravity. Gravity is still pulling them down and that can be showed by marking the changes of their feet, showing the changes in distance. There is GPE acting on them at their top point. A world-class figure skater doesn't defy gravity to remain in the air long enough. This is because the maximum height changes, but very slightly. They are not at the same height, but the displacement is so small that it is hard to see.