cq_1_211

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PHY 201

Your 'cq_1_21.1' 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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Samantha Rogers

PHY 201

Seed 21.1

A ball is tossed vertically upward and caught at the position from which it was released. 

• Ignoring air resistance will the ball at the instant it reaches its original position be traveling faster, slower, or at the same speed as it was when released? 

answer/question/discussion: ->->->->->->->->->->->-> :

 The ball would be traveling at the same speed when it was released because gravity is a conservative force. This is the case when there are no factors, just the acceleration of gravity.

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• What, if anything, is different in your answer if air resistance is present?  Give your best explanation.

answer/question/discussion: ->->->->->->->->->->->-> :

 The ball would be traveling at a lower speed than when it was released because the ball would have lost energy during the toss due to air resistance.

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15 minutes

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7/1/2012 6:00

&#Your work looks very good. Let me know if you have any questions. &#

PHY 201

Your 'cq_1_21.2' 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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Samantha Rogers

PHY 201

Seed 21.2

A typical automobile coasts up a typically paved incline, stops, and coasts back down to the same position. 

• When it reaches this position, is it moving faster, slower or at the same speed as when it began?  Explain

answer/question/discussion: ->->->->->->->->->->->-> :

 The automobile is moving at the same speed as it began on small inclines, if we neglect air resistance and friction, and if gravity is the sole force acting upon the car. However, this is normally not the case, as the angle of the incline induces a greater force upon the automobile, causing its speed to be greater. The smaller the incline, the closer the car accelerates to an object due to the force of gravity.

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A typically paved incline will entail frictional forces. So this is similar to the preceding question about the ball being tossed upward.

Check the discussion at the link. No revision is necessary:

&#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

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. &#

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