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PHY 121
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: ->->->->->->->->->->->-> :
Minimum tension would be at 8cm, where it is stretched the least. Max tension would be at 10cm, where the band is stretched the most. The average tension would be slightly more than 9cm since the more it's stretched, the greater the tension.
@& The average length would be 9 cm. However that's not the tension. Tension is the force, in Newtons. For example, the tension is said to be 3 Newtons when the length is 10 cm.*@
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How much work is required to stretch the rubber band from 8 cm to 10 cm?
answer/question/discussion: ->->->->->->->->->->->-> :
Little work would be necessary to stretch the band an additional 2 cm.
@& work = average force * change in position
What is the average force?
What is the change in position?
What therefore is the work?*@
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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: ->->->->->->->->->->->-> :
Tension force is opposite the direction of motion.
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Does the tension force therefore do positive or negative work?
answer/question/discussion: ->->->->->->->->->->->-> :
Negative.
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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: ->->->->->->->->->->->-> :
Work on the domino is equal to the tension force of the band.
@& work and force are two different things, and cannot be equal
the tension force does work on the domino, equal to the work required to stretch the rubber band*@
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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 is transferred from band to domino.
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At this point how fast will the domino be moving?
answer/question/discussion: ->->->->->->->->->->->-> :
Not sure of this one.
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[ extended discussion of T vs. L and T vs. x including graphs at linked document to be provided ]
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10 minutes
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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. &#