PHY201
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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Seed 18.1
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: ->->->->->->->->->->->-> :
There is the force of gravity that act on the ball vertically against the ball as it rises and with the ball as it falls, there is a force of motion that is acting on the ball in the opposite direction of the motion of the vehicle horizontally
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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: ->->->->->->->->->->->-> :
THe speed is increasing until it reaches a point of rest once it begins to come back down and will return to this speed until it is caught by the child.
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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: ->->->->->->->->->->->-> :
The ball is going in an upward direction vertically and moving somewhat horizontally toward the child as the car is moving forward, the ball will go horizontally in the opposite direction of the motion of the car, it will then come back down and be caught by the child.
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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 path may differ somewhat on a bicycle because there would be more air resistance moving agaist the ball in the horizontal position which may push it more toward the child.
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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 only forces acting on the ball would be the gravity which would be acting on the ball in the same direction, the spped would change by the distance dropped from the roof relative to the time it takes the ball to hit the floor, acceleration would be relative to the speed divided by the amount of time it takes the ball to hit the floor.
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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 ball would appear to have both a slight horizontal motion in the opposite direction of the car as well as a vertical motion as it falls to the ground the child would see the vertical motion first. An observer on the side of theroad would see the ball being dropped and would see the vertical motion of the ball until air resistance hits it and it would go in a horizontal motion in the opposite direction of the car, but if three is little air resistance if tha car is moving slowly the horizontal motion may be barely noticable.
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about 30 minutes
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See as well the discussion at the links. No revision is necessary unless you have questions.
&#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. &#