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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: ->->->->->->->->->->->-> :
There is the upward force at which the child throws it. Once the ball reaches its maximum height, the net force is zero. Then, once the ball begins downward, gravity is acting upon it.
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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: ->->->->->->->->->->->-> :
Initially, the speed of the ball is increasing until it reaches its maximum height. At the maximum height for an instant, the ball has a speed of zero. Then, the speed of the ball increases as it travels downwards. A bell-shaped curve could describe the speed of the ball.
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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: ->->->->->->->->->->->-> :
Since the vehicle is moving, slowly, there will be just slight horizontal displacement. The person would see the ball travel upwards and then come to a stop for just an instant, and then proceed to speed up downward.
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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 only difference I can think of would be that a car is a closed vehicle with a roof, and a bicycle is not an enclosed mean of transportation. Therefore, the air resistance would certainly play a role on the ball. If the kid didn’t bother to catch the ball, the speed of the ball would continue to increase until it hit the ground due to the force of gravity pulling it downward.
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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: ->->->->->->->->->->->-> :
Even though the ball is inside of the car, gravity should still pull it downward at the same rate as it would drop from the bicycle.
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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 path of the ball will be straight down and will have the force of gravity acting upon it.
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20 minutes
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&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your old and new solutions with the expanded discussion at the link
Solution
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