Phy 121
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: ->->->->->->->->->->->-> : 2.4N and 3N
• 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=3N*2cm=6J…that seems very wrong…
not too far off, but the units aren't right; N * cm is not Joules. You should also have used the average, not maximum, force.
• 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: ->->->->->->->->->->->-> : vF^2=sqrt.(2(6)/.02kg) vF=24.5m/s
• If instead the rubber band is used to 'shoot' the domino straight upward, then how high will it rise?
answer/question/discussion: ->->->->->->->->->->->-> : I have no idea where to begin on this problem...I look at the equation for ‘ds and see that I need vAve and ‘dt. Since I don’t know how to find elastic PE as shown in the 2nd step of this seed, I cant find the KE which is making my vF very high and makes the time interval a ridiculous length.
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At least 30minutes
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Can you direct me to where I was susposed to learn about elastic potential energy and tension...I must have over looked an assignment.
You've pretty much got that part. You might be missing the application of gravitational PE to that last question.
See the link and submit a revision if you don't understand completely:
&#Please compare your solutions with the expanded discussion at the link
Solution
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