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: ->->->->->->->->->->->-> :
I think that the car has no change in any of the energy’s when I does not speed up or slow down, nor change direction. The child is giving the ball KE when it is released and has gravitational PE when it falls back down.
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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: ->->->->->->->->->->->-> :
I think that the speed of the ball between release and catch will increase as the ball is thrown up and then decrease as the ball drops down.
the speed of the ball between release and catch will decrease as the ball is thrown up and then increase as the ball drops down
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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: ->->->->->->->->->->->-> :
I think that it will be the same if the path of the ball was observed by someone standing along the side of the road, as if it would be the path of the ball when the child throws it up.
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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: ->->->->->->->->->->->-> :
If the child was on a bicycle, the ball will be vulnerable for air resistance. If the ball is thrown by the child on a bicycle up vertically and the bicycle is going in the horizontal direction, then the bicycle will still be traveling while the ball is coming back down. When the ball hits the ground, the child on the bicycle will be a distance away from the ball when it hit the ground.
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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: ->->->->->->->->->->->-> :
The speed of the ball will increase when the ball is dropped from the inside roof of the car to the floor, because of the gravitational PE. I think that the ball’s acceleration will decrease, because the ball will cover more area in a shorter amount of time.
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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: ->->->->->->->->->->->-> :
The child will see the ball hit the ground not exactly straight up from where the child drops the ball initially. I think that the man on the side of the road will just see the ball falling to the ground straight from the child’s hand.
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45 minutes
You appear to have submitted the two documents for these questions using one form. I've split them into two responses, since the given link is different for the two questions.
&#You should submit a revision of this document, after comparing your thinking with the discussion at the link below. &#
&#See any notes I might have inserted into your document. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your solutions with the expanded discussion at the link
Solution
Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#