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PHY 241
Your 'cq_1_14.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_14.1_labelMessages **
A rubber band begins exerting a tension force when its length is 8 cm. As it is stretched to a length of 10 cm its tension increases with length, more or less steadily, until at the 10 cm length the tension is 3 Newtons.
Between the 8 cm and 10 cm length, what are the minimum and maximum tensions, and what do you think is the average tension?
answer/question/discussion: ->->->->->->->->->->->-> sion:
max 3N min 0N average 1.5 N
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How much work is required to stretch the rubber band from 8 cm to 10 cm?
answer/question/discussion: ->->->->->->->->->->->-> sion:
`dke= 3N*2cm=6Ncm
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3 N is the maximum force, exerted only at the 10 cm length. The force is always less than 3 N, except at the very end. So the work is clearly less than the 6 N cm obtained by assuming that this force acts through the entire displacement.
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During the stretching process is the tension force in the direction of motion or opposite to the direction of motion?
answer/question/discussion: ->->->->->->->->->->->-> sion:
direction opposite motion
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Does the tension force therefore do positive or negative work?
answer/question/discussion: ->->->->->->->->->->->-> sion:
positive work.
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If you multiply a force in one direction by a displacement in the opposite direction, then one of the two is positive while the other is negative. What does that do to the product?
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The rubber band is released and as it contracts back to its 8 cm length it exerts its tension force on a domino of mass .02 kg, which is initially at rest.
Again assuming that the tension force is conservative, how much work does the tension force do on the domino?
answer/question/discussion: ->->->->->->->->->->->-> sion:
6Ncm work done on the domino
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The 3 N maximum force acts only at the first instant.
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Assuming this is the only force acting on the domino, what will then be its kinetic energy when the rubber band reaches its 8 cm length?
answer/question/discussion: ->->->->->->->->->->->-> sion:
6Ncm
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At this point how fast will the domino be moving?
answer/question/discussion: ->->->->->->->->->->->-> sion:
6Ncm=.5(.02kg)v^2
V=24.5cm/s
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The 6 N cm isn't correct, but otherwise your equation is OK. However the solution to your equation is not v = 24.5 cm/s.
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Right overall ideas, but there are errors in the details of your execution.
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