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phy 201
Your 'cq_1_18.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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A child in a slowly moving car tosses a ball upward. It rises to a point below the roof of the car and falls back down, at which point the child catches it. During this time the car neither speeds up nor slows down, and does not change direction.
What force(s) act on the ball between the instant of its release and the instant at which it is caught? You can ignore air resistance.
answer/question/discussion: ->->->->->->->->->->->-> :
Obvously gravity the boy pushing it upward the force of the car moving
When caught the cars force gravity and the boys hands
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Between the instant of release and the instant at which it first touches the boy's hands, only gravity will be acting.
If you regard the instant at which it is caught to be the instant at which it comes to rest, which is certainly a valid interpretation, then the force exerted by the boy's hands would be included for the interval between first contact and the instant at which the ball comes to rest.
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What happens to the speed of the ball between release and catch? Describe in some detail; a graph of speed vs. clock time would also be appropriate.
answer/question/discussion: ->->->->->->->->->->->-> :
it increases in a vertical direction then slows then goes to negaive when it hits the hand it is at zero in a vertical direction
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Describe the path of the ball as it would be observed by someone standing along the side of the road.
answer/question/discussion: ->->->->->->->->->->->-> :
It would be going upward and horzontally so it would be moving in a diaginal upward then a diagonal downward
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The ball is moving at constant velocity in the horizontal direction, and at changing velocity in the vertical direction.
A diagonal would occur if it was moving at constant velocity in both directions.
How would your answer to the question accomodate the changing velocity?
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How would the path differ if the child was coasting along on a bicycle? What if the kid didn't bother to catch the ball? (You know nothing about what happens after the ball makes contact with the ground, so there's no point in addressing anything that might happen after that point).
answer/question/discussion: ->->->->->->->->->->->-> :
The ball would decelerate and as the boy goes forward the ball would end up behind him
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What if the child drops the ball from the (inside) roof of the car to the floor? For the interval between roof and floor, how will the speed of the ball change? What will be the acceleration of the ball? (You know nothing about what happens after the ball makes contact with the floor, so there's no point in addressing anything that might happen after that point).
answer/question/discussion: ->->->->->->->->->->->-> :
It will increase in a negatice vertical direction at a rate of 98 gravity
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What if the child holds the ball out of an open window and drops it. If the ball is dense (e.g., a steel ball) and the car isn't moving very fast, air resistance will have little effect. Describe the motion of the ball as seen by the child. Describe the motion of the ball as seen by an observer by the side of the road. (You know nothing about what happens after the ball makes contact with the ground, so there's no point in addressing anything that might happen after that point).
answer/question/discussion: ->->->->->->->->->->->-> :
For the kid it will go backward and downward
For an outside observer it will go forward and downward
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What sort of path does it follow as it goes forward and downward?
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7 minues
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A child in a car tosses a ball upward so that after release it requires 1/2 second to rise and fall back into the child's hand at the same height from which it was released. The car is traveling at a constant speed of 10 meters / second in the horizontal direction.
Between release and catch, how far did the ball travel in the horizontal direction?
answer/question/discussion: ->->->->->->->->->->->-> :
5 meters
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As observed by a passenger in the car, what was the path of the ball from its release until the instant it was caught?
answer/question/discussion: ->->->->->->->->->->->-> :
An elongated upside down u
It would go diagonally upward till it slows to zero vertical velocity then it goes diagonally downward
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An elongated upside down u doesn't involve any diagonals. A diagonal would be a straight line.
As it turns out the vertical position is a quadratic function of time and the horizontal position is a linear function of time. The result is that the path is parabolic.
Your 'elongated u' is a good description; the fact that the path is a parabola is even more detailed, and will be important later.
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Sketch the path of the ball as observed by a line of people standing along the side of the road. Describe your sketch. What was shape of the path of the ball?
answer/question/discussion: ->->->->->->->->->->->-> :
parabola upside down
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Good.
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How fast was the ball moving in the vertical direction at the instant of release? At that instant, what is its velocity as observed by a line of people standing along the side of the road?
answer/question/discussion: ->->->->->->->->->->->-> :
6.26 m/s
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If the ball was moving at 6.26 m/s in the vertical direction, then at 9.8 m/s^2 it would take over 0.6 seconds to come to stop rising, before falling back down.
It only takes 1/2 second to go up then back down.
You need to show your work.
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Positve verrtically at 6.26 m/s and horizontally 10 m/s
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How high did the ball rise above its point of release before it began to fall back down?
answer/question/discussion: ->->->->->->->->->->->-> :
1.565 m
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I don't believe this is correct. You need to show how you got your result.
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