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phy 201
Your 'cq_1_15.1' 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?
answer/question/discussion: ->->->->->->->->->->->-> :
8 cm - 0 N
10 cm - 3 N
Minimum - 0 N
Maximum - 3 N
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• Assuming that the tension in the rubber band is 100% conservative (which is not actually the case) what is its elastic potential energy at the 10 cm length?
answer/question/discussion: ->->->->->->->->->->->-> :
PE = F x ds
.01 m
10cm x 3 N = .03 N
@& The rubber band only exerts tension between the 8 cm and the 10 cm lengths.
So the displacement through which a force is exerted in only 2 cm, not 10 cm.
3 N is the maximum force, but it isn't the avearage force. The force at the 8 cm length is 0 N, and the force increases steadily to 3 N at the 10 cm length.
What therefore is average force, the displacement through which it is exerted, and the work done by that force?
You will end up multiplying N by cm, as you did in your solution. Note that when you multiply N by cm you get N * cm, not N.*@
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• If all this potential energy is transferred to the kinetic energy of an initially stationary 20 gram domino, what will be the velocity of the domino?
answer/question/discussion: ->->->->->->->->->->->-> :
20g
.03 kg m/s /.02 kg = 1.5 m/s
@& When you complete the preceding correctly you will have figured out the work done, in N * cm.
If that work goes into kinetic energy, as it willl if all the potential energy is converted to kinetic energy, then since the KE started out as zero the KE gained by the domino will be equal to that amount of work.
KE is 1/2 m v^2. Set 1/2 m v^2 equal to KE, solve for v, and plut in the KE and the mass m to see what you get.*@
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• If instead the rubber band is used to 'shoot' the domino straight upward, then how high will it rise?
answer/question/discussion: ->->->->->->->->->->->-> :
1.5 m/s/ 9.8 m/s^2 = .152 s
Well I know to use 9.8 because of gravity
But I’m unsure what to plug in? &&&&&&
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20 min
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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. &#