Section+6

=__//**Section 6- Newton's Third Law: Run and Jump**//__=

What do you see?
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The wall gets pushed in by the kid and the kid then gets pushed back. To every action, there is an action back.

What do you think?
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You should get into a squat position and then push with your feet so your feet will end up in the air. You want to transition your push with the heels to the toes quickly.

Investigate
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Part A
1a) your acceleration is the instant you push off the wall and start moving and the direction is away form the wall, and it lasts for as long as your going back b)the speed is never constant because you're either accelerating positively or negatively, if there were no friction you would never stop and youd keep accelerating c) the source of the push is both the push from the wall slightly and the push from your legs the object that pushes on your mass is the wall.the direction of the push is backwards d) you push against the wall but you push forward e) the force you put against the wall is much greater than the wall against you 2)he moved backwards b)both him pushing against the other kid and the other kid pushing against him c)same as the first kid d) same as B 3)your foot pushes forward and up against the floor, the force the you apply to the floor is much more than the floor applies to you b)its harder to run because of friction but i don't see why it wouldn't be possible to run in terms of force 4a) the person pulling harder accelerates quicker

Free body diagram- indicates all the forces acting on an object. A book on table: 2 forces- weight and normal force book falling: 1 force- just gravity

Part B
3) the stick bends downward 4a)about .5 m b)with each 1N it goes down about .5 cm c) the washer does cause stick to deflect however since its not as heavy as the weights it does not appear to deflect as much d)



Physics Talk
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Newton's third law of motion states: For every applied force, there is an equal and opposite force. The two forces always act on different objects. Examples: A student pushes against a wall, an the wall pushes against the student Two students on different skateboards push against each other. Somebody pushes on the floor backwards, and the floor pushes you forwards.

Free-body diagram- a diagram showing the forces acting on an object. center of mass- this is the point which all the mass of an object is considered to be concentrated How Newton described his third law of motion: 1. For every force applied to object A by another object B, there is an equal and opposite force applied to object B by object A. 2. If you push or pull on something, that something pushes or pulls back on you with an equal amount of force in the opposite direction. This is called the inescapable fact because it happens every time. 3. Forces always come in pairs.

Checking Up Questions
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1. Newton's third law of motion states for every applied force, there is an equal and opposite force. The two forces always act on different objects. 2. It is called the normal force and can be represented as Fn. 3. A free-body diagram shows the forces acting on an object.

Physics to Go
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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. 3. the deflection of the scale is your weight 4. The more force exerted by the bat, the farther the ball goes. Bats break because there bonds in the bat just break because there isn't enough normal force. 5. same 6. normal force, weight 7. provides a slow down cushion

**Ball In A Cup**
//__Jason Schneiderman__, Jeff Diorio, John Forte, Physics, Period 4, Group 4// //January 5, 2011//

Determine the distance of where the cup should be placed so the ball will land in it. What is the distance the cup should be placed from the table so the ball rolling off of it is to land in it?
 * __Objective__**

We will measure the ramp and time the ball going down to find an average speed. The speed of the ball at the bottom of the ramp can be determined with d=1/2(Vi+Vf)t. Then, we will make a horizontal/vertical table and find the horizontal distance. To do this we first must find the time it will take to reach the floor using d=1/2AT^2, where acceleration is -9.8 due to gravity and the distance is measured between the ground and the table. Then using D=VT we can find the horizontal distance. This horizontal distance will be the distance from the table the cup should be placed.
 * __Theory__**

The ball was rolled down the ramp several times and my group timed the runs. We averaged that, measured the distance of the ramp, and used v=d/t. We also measured the vertical distance by using a string with a weight attached to it, marking the spot it hit, and measuring the table to that.
 * __Materials & Methods__**


 * __Data & Calculations of Group 4__**


 * || Horizontal || Vertical ||
 * Distance || .36m || .84m ||
 * Time || .414 s || .414 s ||
 * Acceleration || .3112 m/s/s || -9.8 m/s/s ||
 * Vi || 0 m/s || 0m/s ||
 * Vf || .8714 m/s ||  ||


 * Trial || Time runs ||
 * 1 || 2.87 m/s ||
 * 2 || 2.85 m/s ||
 * 3 || 2.7 m/s ||
 * 4 || 2.82 m/s ||
 * 5 || 2.74 m/s ||
 * 6 || 2.72 m/s ||
 * 7 || 2.83 m/s ||
 * 8 || 2.85 m/s ||

Average time of ball rolling down ramp = **2.8 m/s**


 * Calculations to get the horizontal distance:**


 * Calculation to determine the velocity final at the end of the ramp**


 * D=(1/2)(Vi+Vf)T**
 * 1.22m=1/2(0+Vf)2.8**
 * Vf=.8714m/s**


 * Calculation for time**
 * D=(1/2)AT2**
 * .84m=(1/2)(9.8)T2**
 * T=.414 s**


 * Calculation for horizontal distance**
 * D=VT**
 * D=(0.8714)(.414)**
 * D=0.36m**

For this experiment is important to go in steps to get the final answer and use the horizontal/ vertical chart. This is the right approach, but everyone’s answer would be different considering the angle of the ramp. We encountered a problem in which we used the wrong equation and ended up with exactly half of the distance. When we retried with the real distance we hit the cup. That is how we knew we did the equations the right way the second time.
 * __Analysis & Discussion__**

The cup should be placed .36 m from the lab table so that the ball would land in it.
 * __Conclusion:__**