Chapter+2

= = = = toc = = = = sections= purple class discussions/ activities = fushia homework = orange = Chapter 2 =

AcP Text Book

What do you see pg. 132
November 19, 2010 -Person is winding up to kick the ball, when its kicked it goes over the goal out the picture (so much force you hear sound of the ball being hit so hard) - The boy is playing with the dog, the ball only moves a little bit - Mouse is kicking the ball looks like it is not going anywhere -ball follows curved path

Investigate Newton's First Law
November 19, 2010 In this Investigate, you will use a track and a ball to explore the question, “When a ball is released to roll down track and up the opposite side of the track, how does the vertical height that the ball reaches on the opposite side of the track relate to the vertical height from which the ball is released?”

Make a hypothesis. Answer the question to the best of your ability at this time. ! It will go the same height

1c. Use the default track and all other default settings. Use the measuring tape to measure the initial height. ! 2.00m 1e.Place your cursor at the height point that the skater reaches on the opposite track. Measure the vertical height of this mark. ! 4.00 2a.Predict where the skater will reach his highest position if he begins at the same place as before. ! around the same place 2b. Explain why you think so. ! You’re starting at the same height but your slope is different, when you look at the person going back and forth sometimes it is going higher other times it is going lower 3a. How close was your prediction to the actual outcome? Why do you think your prediction was “close” or “way off”? ! pretty close 3b.Measure the vertical height where the ball stopped. Write a sentence that fully describes the movement of the ball in terms of its starting and recovered vertical heights. ! When I measured the height of where the ball stopped it was 4.10m. It should be less then or equal to 4.10 you are either going to lose energy or keep the same energy you will never gain it 4a. First record your prediction. ! it goes the same height 4b. Compare your prediction with the outcome. ! it looks like it’s the same height 5a. No matter how far along the horizontal track the skater rolls, would he ever recover his starting height? ! no 5b. How far do you think the skater would roll? ! almost halfway 5c. What would keep the skater rolling on a horizontal track? ! him putting more force in, or a small bump or hill 5d. Try this on the simulation. What happens? ! doesn’t work 6a. What happens to the length of the opposite track the skater rides as the slope decreases? ! increase, but rising to close to the same heigh 6b. What happens to the final vertical position on the opposite track the skater rides as the slope decreases? ! you should get up to that height or less 6c. Remember that we are ignoring friction. The initial question was: “When a ball is released to roll down track and up the opposite side of the track, how does the vertical height that the ball reaches on the opposite side of the track relate to the vertical height from which the ball is released?” What is your answer to this question? ! It is the same, a little lower because it starts off with a lot of acceleration, but as it keeps going it slows down slightly causing the ball to not go as high 6d. If the opposite track was infinitely long, and frictionless, when would the skater stop? ! never

Physics Talk Summary p.134
November 22, 2010

Checking Up Questions p.138
November 22, 2010 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. 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. Force needs to act on an object to stop it from moving at a constant speed. 4. A force stops a rolling ball from rolling forever. 5. The object with the greatest mass will have the greatest inertia. 6. It is important to establish a frame of reference when describing the speed of the ball, because you need to know whether your should find the vantage point that is respective to the ground or the train.

Physics Plus p.139-141
November 23, 2010 sin(theta)= oppisite/ hyp theta= invSin(oppisite/hyp) cosine(theta)= adjacent/hyp theta= invCos(adjacent/hyp) tan(theta)=oppisite/adj theta= invTan(opposite/adj) 1a. .22 1b. .33 1c. .52 3a. .41 3b. .89 3c. .99 3d. .615 4. The object would keep moving and never stop.

Respond p.141
November 23, 2010

What do you See?
November 30, 2010 Walking slower in the first picture, footsteps are closer together

Investigate
1a. Same even distance 1b. Even distance more spread out 1c. Even distance closer together 1d. It even and then gets farther apart as the speed gets faster. 6a. 7a. It is the same distance apart 7b. Yes the speed was constant, because the dots were an equal distance away 8a. The dots were closer at a slower speed, but as we increased speed the dots get farther apart 8b. Its moving faster 8c. Dots are farther apart because speed is increasing 9a. 9b. Started constant, then it increased, then decreased then increased 10a. 10b. It will start out far apart and then move closer and closer 11a. When they speed up there is a positive acceleration, and when they slow down its a negative acceleration

Physics Plus pg. 152
December 2, 2010 1.  Negative means it is changing direction 100 m/s^2 is same as ten g's of acceleration (The fastest roller coaster, Kingda Ka, is four g's) Fighter pilots experience 10g's  2. -5 m/s^2 is half a g This happens in bumper cars (rubber on outside and compresses the impact when you hit the other bumper car) This also happens with airbags in a car (when you jolt forward the airbag comes out and helps slow you down so you do not hit the steering wheel) 3a. -5 3b. -5 3c.

Physics Talk 148
December 2, 2010 acceleration- a change in the velocity of an object over time average speed- distance traveled divided by the time it took to travel that distance instantaneous speed- the speed measured during an instant: the speed as the time interval approaches, but does not become zero

Checking Up 141
December 2, 2010

Physics to Go 1- 13
December 2, 2010 1. Instantaneous speed: speed at a certain instant and average speed is the speed of the entire distance 2a. v=1km/15s v= .06 m/s 2b. v= 84m/6s v= 14 m/s 2c. v=9.6km/2h v=4.8 km/h 2d. v= 400km/4.5 h v= 89 km/h 3a. positive acceleration 3b. positive acceleration 3c. no acceleration 3d. negative acceleration 3e. no acceleration 3f. no acceleration 4a.A,D 4b. B 4c. A 4d. C 5. length divided by .1 6a. a=(0-45km/h)/9s a= -5 m/s 6b. negative 7a. constant 7b. speeding up 7c. speeding up, slowing down 7d. slowing down, speeding up 8. v=100mi/2 v= 50mi/h 9. no, this is the average speed over the entire distance 10. .. . . . . . . . . 11. 20m/s 12. yes, they can move 10m/s 13.

What Do You See? pg. 157
November 29, 2010 It's a heavy ball, because the stick is bent

What Do You Think? pg. 157
November 29, 2010 What is force? A push or pull that acts on an object *Gravity only pulls never pushes How will the same amount of force affect a tennis ball and a bowling ball differently? The tennis ball will accelerate at a greater rate than a bowling ball will accelerate. This happens because the mass of the bowling ball is more.

Investigate pgs. 157-159
November 29, 2010 2a. The motion of the cart accelerates 3a. The cart accelerates and a faster rate 3b. It is similar because they are both accelerating. 3c. It is different because the more force, the faster the car accelerates 3d. The greater the constant force pushing on the object, the faster the car will accelerate. 4a. It accelerates faster 5a. It takes longer to accelerate. 5b. When equal amounts of a constant force are used to push objects having different masses, the more massive the object the more time the object takes to accelerate. 6a. You would need more force to move the larger object and less force for the smaller object. 8a. The ruler bends slightly. 9a. It bends more with each coin that you put on the ruler. 9b. Ten pennies is a small force and fifty pennies is a big force. 9c. The weight of the pennies.

Physics Talk p.160
December 3, 2010 It is difficult to push on an object with a constant force because the object would move faster and faster As you push on a more massive object with the same force, it does not accelerate that much. Newton's Second Law of Motion: the acceleration of an object is directly proportional to the unbalanced force acting on it and inversely proportional to the object's mass. The direction of the acceleration is the same as the direction of the unbalanced force. weight:: the vertical, downward force exerted on a mas as a result of gravity. free- body diagram: a diagram showing the forces acting on an object

Checking Up pg. 167
1. Newton's Second Law of Motion is where acceleration of the object and the unbalanced force vary directly. The acceleration goes in the direction of the unbalanced force. 2. The acceleration will be smaller, if the mass increases 3. According to the equation m=f/a, you would need the forces or acceleration to find out that the mass is 30N 4. The mass and weight would increase if you went on a planet the had a higher acceleration due to gravity

Physics To Go pg. 171
1.
 * Newton's Second Law || F = || M x || A ||
 * Sprinter beginning 100m dash || **350N** || 70kg || 5 m/s^2 ||
 * long jumper in flight || 800 N || **80 kg** || 10 m/s^2 ||
 * shot-put ball in flight || 70 N || 7 kg || **10 m/s^2** ||
 * ski jumper going downhill before jumping || 400N || **80 kg** || 5 m/s^2 ||
 * hockey player "shaving ice" while stopping || -1500N || 100 kg || **-15 m/s^2** ||
 * running back being tackled || **-3000 N** || 100 kg || -30 m/s^s ||

2a. The long jumper in flight and the shot - put ball in flight 2b. Yes, because the hockey play is pushing on the ground and the ground is pushing back 2c. Yes, because the force and acceleration are always in the same direction 3. 140 m/s^2 4. .8N 5a. **1st law greater the mass the harder it is to change the motion (law of initeria**) 5b. **more force is required to change the speed if its mass is greater** 6. 9.8x.1= .98 "The Newton Burger" 7a.
 * || metric || english ||
 * weight || N || lbs ||
 * mass || kg || slug ||

4.38N=1 lb AND 1kg= 2.2 lbs 7b. **65.7** 8. 9. 10. 90N 11. 50N each 12. .18 m/s^2
 * acceleration due to gravity = 9.8m/s^2**
 * w=mg**
 * 657**

Investigate
1a. same time 2a. same time 3a. no 3b. the one close to the edge goes farther (this is the coin at rest) 3c. PICTURE 4a.same time 4b. The change in height affects how far the coins travel horizontally. The higher it is, the further the coins will travel vertically. Part B 1a. I predict that ball will land behind you, because when you throw it up you are still getting pushed on the chair so it will land behind you. 2a. We saw that the ball stays with the person in the chair. The ball stays moving with the speed of the person. 2b. The factors that affect the range of the ball are speed, and the height that the ball is thrown up in the air.

What do you see? Page 174
December 8, 2010 Ball is flying in the air

What do you think? Page 174
December 8, 2010 The force you are putting into the ball that is flying in the air will affect how fast it is going to accelerate which also affects when it lands

Physics Talk Page 177
December 9, 2010 Projectile: an object traveling through the air or any other medium

Checking Up Questions Page 178
1. Yes, because both the ruler and the pen have the same mass and projectile. 2. No, the vertical velocity always changes. If the object is going up, it slows down, and if the object is falling down, it speeds up. 3. The ball's velocity is 0m/s, and the acceleration is -9.8m/s^2.

Physics Plus Page 180
December 9, 2010

Physics to Go Page 182
December 9, 2010 1.2.3. PICTURE 4. The coins part is believable because we can see it happening. The bullets move so fast, making it harder to see, and the bullet that is shot covers a lot of ground in short amount of time. 5. The faster pitch will land further away than the slower pitch, but that gives it more time to start projecting towards the gorund. 6. Ball and person are at the same distance 7. They hit the ground at the exact same time. 8. 9a.12 9b. 24 10a. 8.5 10b. 4.25

What Do You See?
December 13, 2010 Parabola Dotted lines above the kids heads Score board has Algebraic numbers on it The girl kicks the ball straight up into the air The boy kicks it on a angle Launch vs. landing is the same

What Do You Think?
December 13, 2010 wall in the back can be used a reference because it is a horizontal line

Investigate
December 14, 2010

Physics Plus p. 190
A ball rolls off a table and lands on the floor

Decription of motion in a vertical direction As soon as the ball leaves the table it begins to fall downward a distance of "y". As it falls it begins with a velocity of V(y)i=0 AND accelerates at 9.8 m/s^2. this means it speeds up as it falls. The time it takes to reach the floor is "t'

Vertical Variables: y V(y)i a=g=9.8m/s^2 (g=-9.8 m/s^2 if we define "down" as negative) t V(y)F

Vertical Equations OR y=1/2gt^2 (if V(y)i=0)
 * y=1/2gt^2+V(y)it

g= (VyF-Vyi)/t

y=1/2(Vyi+VyF)t

VyF^2=Vyi^2+2gy

V=d/t *DOES NOT APPLY IN THE VERTICAL BECAUSE ACCELERATION CANNOT EQUAL ZERO BECAUSE THERE IS A CHANGE IN SPEED*

Horizontal Motion: -The ball moves at a constant speed as it moves a distance "X". It moves horizontally a time of "t" (SAME AS IN THE VERTICAL DERECTION) -Ax=0; So Vxf=Vxi (SAME AS THE INITIAL) Horizontal Variables X,T,Vx ONLY (because VxF=Vxi

A ball is pushed such that it rolls across the table at a constant speed of 5 m/s. The ball rolls off the table which is 73 cm tall, the ball lands on the floor.

HOW TO SOLVE: 1. write givens 2. Calculate "ty" (use the y column) y= 1/2gty^2+Vyit -.75m=1/2(-9.8)ty^2+0 t= .39s
 * Variable || X || Y ||
 * d || __x=1.95m__ || -75 cm =-.75m ||
 * T || __?=.39s__ || __?=.39s__ ||
 * Vi || 5 m/s || 0 ||
 * Vf || 5 m/s || __?=-3.8m/s__ ||
 * a || 0 || -9.8 m/s^2 ||

Vx=x/t x=V(x)t=5(.39)=1.95m

a=(VyF-Vyi)/t -9.8=VyF-0/.39 VyF= -3.8 m/s

What is Vf (not Vyf or VxF, but Vf)! USE PYTHAGOREAN THEOREM 6.28

#1 and #2 pg. 192
1. y=1/2at^2 t=.58s .58 (7)= 4.13m 4.13 (2)= 8.26m

2. g=1/2at^2 1.5= 1/2(9.8)t^2 t=.55 sec .55x=

PTG #1-10
1. 45 degrees 2a. the ball would be up in the air for a more amount of time 2b. The ball would be up in the air for a less amount of time 3a. 3b. 75 degrees 4. The angle is less because the long jumper has to run really fast horizontally 5. The higher the horizontal velocity, the higher the hypotenuse (which is used to determine the distance of where a long jumper lands) 6a. downward 6b. east 7. Given: Vertical velocity: a = (vf - vi) t vf=9.8(3) vf = -29.4 m/s
 * var. || x || y ||
 * d ||  ||   ||
 * vi || 35 || 35 ||
 * vf || 5m/s || 0 ||
 * d || 5 m/s || 0 ||
 * a || 0 || -9.8 m/s^2 ||

7b. 5 9.8 = (vf) /1 vf = 9.8m/s 7c. d = 1/2(9.8)(3)^2 d = 44.1 meters 8. 45 degrees 9. 10a. Down 10b. 100 = 1/2(9.8)t^2 t = 4.51 seconds 10c. 20 = d/4.51 d = 90.35 meters

Ball In Cup
distance ramp black distance: 14cm whole thing: 1.35 m
 * || speed ||  ||   ||
 * trial one || 3.03 ||  ||   ||
 * trial 2 || 3.05 ||  ||   ||
 * trial 3 || 3.04 ||  ||   ||

Ball In Cup Lab

What Do You Think? pg .198
January 3, 2011 - Guy pushes wall in - Wall pushes back on him making him move backwards

Instruction Manual on How to Jump
January 3, 2011 1. bend your knees 2. push through your feet through your toes quickly 3. push back up and straighten your knees 4. push your feet upwards while your pushing upwards

Investigate
1a. when the person is changing direction pushing of the wall. however long they are in motion. away from the wall 1b. You are constantly accelerating, and you will never stop 1c. The force will be a push. The The object that pushes you causing you to move is the wall. This push causing you to accelerate is negative 1d. You push against the wall in a positive direction 1e. The two forces would be the same 2a. If the two forces are equal student A will travel backwards 2b. The motion of student A depends on the force of student B 2c. Student B travels backwards 2d. Student A caused the force of student B 3a. The force is coming from the floor. The amount is the same but in the opposite direction 3b. It is not possible to walk or run on an extremely slippery ice rink because there would be little to no friction. PART b 3a. When you put a coin on the meter stick a deflection occurs 4a. regular: 8cm 100g: 7.75cm 100g + 1N: 7 5/8 100g + 2N: 7 1/2 4b. picture 4c. The meter stick is deflecting, because when the weight is put on it it pushes down on the weakest part of the meter stick

Summarize Physics Talk, p. 201
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 come in equal and opposite pairs. Free body diagram: a diagram showing the forces acting on an object center of mass: the point at which the mass of an object is considered to be concentrated

Complete Checking Up, 1-3, p. 205
1. Newton's third law is that for every force there is an equal force pushing back 2. gravity and normal force 3. a free body diagram illustrates forces acting on an object

Complete PTG, p. 208 1-7
1. yes, the hand is exerting the same force as the ball 2. the chair pushes back with an equal force. There is deflection but it is not enough to see. Stressing the chair will cause it to stretch. Restoring force is the normal force 3. the deflection of the scale measures the normal force. 4. The more force exerted by the bat, the farther the ball goes. Bats break because it is not able to provide enough restoring force 5. the heavier football player will push the small one further. Action & reaction 6. hockey player pushes on board and board pushes back on hockey player 7. With the glove the there is more space between ball and hand

Physics Plus
January 5, 2011

Physics to Go
January 6, 2011 1. Yes, 2. stressing the chair causes it to stretch, and the more you stretch it the more it pushes back on you which is the restoring force. When someone sits on your lap the forces pushes more 3. It deflects a restoring force, it measures the normal force 4. The forces are the same. The bats break because it's not able to push back because the atoms in the back are broken. The bat can not restore the normal force 5. Action reaction one pushes on the other and he pushes back 6. The hockey player pushes on the wood and it pushes back 7. The glove provides more area to stop the ball slower

What Do you See?
January 6, 2011 It is easier to pull the shoe on the ice rink than it is in the sand There is less friction on the ice

What Do You Think?
Soccer cleats need to grip the grass and mud Ballet shoes need to be able to turn

Investigate
1a. 5 newtons, Nike 1b. It has ridges on the bottom that affect the friction 2a. We will compare our shoe with Jeff's shoe which is bigger, weighs more, and is a different brand, look at the bottom of the shoe, and the force it takes to pullit two shoes and spring scale just compare them 3a. Smooth surface with low friction 3b. 1 newtons, it was a constant 1 newtons the whole time showing that we kept it at a constant speed 3c. 1/5= .2 4a. (used 500g) takes 4b. 3 newtons force: .3 4c.. Yes mu increased when we doubled the weight of the shoe 4d. It would be a lot greater because an athlete weighs a lot more

Physics Talk pg. 212
January 10, 2011 Friction: force that resists relative motion between two bodies in contact Normal force: force acting perpendicularly or at right angles to a surface Coefficient of sliding friction- dimensionless quantity symbolized by a Greek letter; its value depends on the properties of the two surfaces in contact and is used to calculate the force of friction

Checking Up Questions pg. 214
January 10, 2011 1. There is no horizontal acceleration, because the shoe is moving at a slow and constant speed. This means there is a 2nd force of friction on the shoe of which force is applied in the equal and opposite direction. 2. The coefficient of friction has no units because it is a force divided by a force. This means it has no unit of measurement. 3. It depends on the properties of the two surfaces. It's used to calculate the force of friction.

Physics to Go pg. 218 #'s 1-5
1. The sport I chose was football. When the ground is wet you want the most friction so you won't slip. Football players wear a certain type of shoe so they won't have to worry about slipping in wet weather 2. A sport with little friction would be luge. The players want the ball to have little to no friction so that they can keep the ball going. 3. The factors that would affect it is what type of surface the ground was. 4. They have different shoes for each surface because there is a major difference between clay and grass courts. 5.?

What Do You See?
January 14, 2011 pole vaulting to get onto the roof

What Do You Think?
January 14, 2011 1. factors are speed 2. how long the pole is 3. mass 4. technique

Investigate
January 14, 2011 1a. put the penny on the edge of the ruler. When you push the ruler down more and let go, the restoring force of the ruler causes the penny to go higher as if you were to push the ruler down only a little bit 1b. How much you push it down, where you angle it, and how flexible the ruler is 5a. Line A was very close to the starting point so the ruler deflected less. As you moved farther away from the starting point the ruler deflected more. 5b. The faster he runs the more it bends 8&9. We pushed the penny down one cm and it shot up a little. As we measured more and more increasing by each cm the penny shot higher up into the air. After pushing down to 6cm we finally hit the ceiling.

Physics Talk
January 18, 2011 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 Law of Conservation of Energy: energy can't be created or destroyed; it can be transformed from one form to another, but the total amount of energy remains constant Work- the product of the displacement and the force in the direction of the displacement Elastic potential energy- the energy of a spring due to its compression or stretch

Physics Plus
January 18, 2011 For work the distance must be the same direction as the force Work: product of force on an object and the distance the object moves because of this force w=fd ex: A 25kg object is lifted - how much work is done on the object if we still lift it 1.5m? W=fd w=Fgd w=(mg)d w=25x9.8x1.5=368 joules A joules is a measure of work AND a measure of energy This means that Work and Energy ARE EQUIVALENT Energy is used to do work; Work is done to produce energy work = energy

FORMULA 1 W=Fd (work is done hy # force whose direction is in the same direction as the motion)

FORMULA 2 epe= 1/2kx^2 x is distant that is being stretched or compressed k is ratio of amount of energy

FORMULA 3 GPE=mgh m: mass g: acceleration due to gravity h: height

FORMULA 4 ke= 1/2mv^2

Fs=KX <--- force of a spring EPE=1/2kx^2 < energy in a spring

k=f/x k=mg/x k=(.2)(9.8)/.22 k=8.9N

m=100g = .1 kg h=1.20m gpe=mgh =.1kg(9.8)1.2m = 1.18j

b. the spring gives the toy KE which then gives it GPE. The entire process BB2 does work m spring --> EPE(comes from work) --> converts to --> KE --> converted to -->GPE KE= 1/2mv^2 GPE CAME FROM KE so... GPE = KE 1/2mv^2=1.18J c. x=2cm=.02m k=? EPE=1/2kx^2 KE came from the EPE EPE=KE=1.18J

1/2kx^2=1.18j 1/2k(.02)^2=1.18j K=5900 N/M d. Fs=? F=kx F=(5900N/M/)(.02) F=118N

Checking Up
January 19, 2011 1. Work is required for the energy of an object to change. 2. The penny gets its energy from the ruler when it gets pushed down 3. The pole vaulter gets the energy needed by running 4. work,kinetic energy, gravitational potential energy, and spring potential energy are measured in joules.

Physics To Go
January 20, 2011 1. Person throws shock put --> EPE(comes from work) --> converts to --> KE --> converted to -->GPE 2. Person hits golfball --> EPE(comes from work) --> converts to --> KE --> converted to -->GPE 3. 1/2mv^2=mgh 1/2v^2=gh 1/2(144)=9.8h 72=9.8h h=7.35m 4. The pole doesn't determine this the speed does 5. There's no calculation, when you flex it some of the bonds are broken 6. GPE = KE 7. mgh=1/2mv^2 v=9.4 8. GPE = KE mgh=1/2mv^2 v=(SQUAREROOTOF)2gh v=(SQUAREROOTOF) 2(9.8)(100) v=44m/s 9a. k=1500N/M x=25cm=.25m w=? w=1/2(1500N/M)(.25)^2 w=47J 9b. KE=W=47J 1/2mv^2=47J 1/2(.1)v^2=47j 10a.k=315 N/M w=? w=EPE=1/2kx^2 w=1/2(315)(.30)^2 w=14J 10b. f=kx=(315)(.30)=95N 11. GPE = KE= EPE mgh= 1/2kx^2 (.04)(9.8)(1m)=1/2(18)x^2 x=.2m 12. f=ma 1N=kg(m/s)^2 13. diver uses her kinetic to run and jump on the board using GPE KE EPE KE GPE KE 14. set the ball (KE) when it falls (GPE)

What Do You See? pg. 234
January 31, 2011 -Person is a projectile -Girl is timing him - He's really big - Jumping higher than the bird - Spinning around in the air

What Do You Think? pg. 234
January 31, 2011 The hang time of athletes might have an affect You cannot defy gravity, you just have to jump and spin really fast

Investigate pg. 235
January 31, 2011 1a. It is in the air for 20 frames. 1b.Time in air=20(1/30) Time= .67 seconds 1c.It looks like the person is floating when he reaches his maximum height. 2a. 31(1/30)=1.03 seconds 2b. There is hang time, but there is nothing magical about it. 3a. Weight (N)= weight (lb)x (4.38N/lb) Weight (N)= 175 (4.38) Weight N= 766.5 3b. Weight =mg 766.5= 4a. .91 meters 5a. 1.05m 5b. 1.05-.91=.14m 6a. 1.22m 6b. 1.22-1.05=.17m 7a. 1.22-.91=.31m GPE=mgh GPE=.31x9.8x165 GPE=501.27J 7b. GPE=EPE=501.27J 7c. 1.05-.91=.14m GPE=.91x9.8x165 GPE=226.3J

Physics Talk pg. 237
January 31, 2011 - When you are in the ready position, you have elastic potential energy. If you were a spring, the elastic potential energy would be present due to compression of the material making up the spring. In your case, the potential energy you are going to use is present due to chemical reactions waiting to happen in your muscles. As you move toward the launch position, you have exchanged your EPE for an increase in GPE and KE. As you rise in the air, you lose KE and gain GPE. - The energy of 3 positions must be equal.

Checking Up Questions Page 241
February 1, 2011 1. The work being done allows the jumper to transfer his energy from the ready position to the launch position. 2. In the launch position contains GPE & KE. The peak position is where the energy becomes GPE. 3a. light 3b. sound 3c. chemical

Physics Plus
February 3, 2011

Physics To Go 1-17 pg. 244-245
1. 490 joules 2. KE(pushing the bobsled) - GPE - KE (bottom of hill so GPE drops) - E=0 3. Do a strobe photo and show that he is not defying gravity just slowing down while in the air 4. Some one else would need to have to provide that the claim is true, because even if I person looks like he is defying gravity does not mean he actually is 5. Increase force by using muscles (create more force) and lose weight 6a. 1.0x1.0=1 J 6b. 1.0x10=10 J 6c.10x1.0=10 J 6d. 100x.1=10 J 6e. 1.0x100=10 J 7. gpe=mgh a. same answers as 6 8. GPE=KE 9. W=fd W=(50N)(43m) W=2150 J F:5.1 kg D:43 w=5.1x43 w= 219.3N 10. ke=1/2mv^2 ke=1/2(62)(8.2)^2 ke= 2084.44J 11a. f=ma 30=5a a=6m/s 11b. fgh 30x18.75 = 12a. 12b.3200/1200 a= 2.7m/s 15. KE to EPE to KE to GPE to KE 16. GPE to KE to EPE to KE 17. KE