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Phy 231
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.
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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: ->->->->->->->->->->->-> :
ave = (0+3)/2 = 1.5 N
Min is 0 and max is 3
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How much work is required to stretch the rubber band from 8 cm to
10 cm?
answer/question/discussion: ->->->->->->->->->->->-> :
W = F * d
W = 3 * .02
W = 0.06 J
@& Multiply ave force by displacement, not max force by 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: ->->->->->->->->->->->-> :
Opposite
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Does the tension force therefore do positive or negative work?
answer/question/discussion: ->->->->->->->->->->->-> :
It does Positive Work.
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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: ->->->->->->->->->->->-> :
Fnet = m * a
3 = 0.02 * a
a = 150 m/s
vf^2 = v0^2 + 2*a (x-x0)
vf^2 = 0 + 2 * 150(0.1-0.08)
vf = 2.45 m/s
dw = (0.5*0.02*2.45^2)-(0.5*0.02*0)
dw = 0.06 J
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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: ->->->->->->->->->->->-> :
KE = 0
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At this point how fast will the domino be moving?
answer/question/discussion: ->->->->->->->->->->->-> :
vf = 2.45 m/s
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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
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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