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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.
** CQ_1_15.1_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?
answer/question/discussion: ->->->->->->->->->->->-> :
The minimum tension occurs when the rubber band is at/around the length of 8 cm. Thus, the minimum tension is 0 Newtons at 8 cm. The maximum tension, 3 Newtons, occurs when the rubber band is 10 cm in length.
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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: ->->->->->->->->->->->-> :
The rubber band will gain all of its tension. The elastic potential energy is equal to the work required to stretch the rubber band. Average Force=1.5 N (( 0 N + 3 N)/2 )
'dW= f_ave*'ds
'dW=1.5N*2 cm=3N*cm
Convert N*cm to N* m
3N*0.1 m=0.03N*m=0.03 Joules
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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: ->->->->->->->->->->->-> :
20 g domino=0.03 J
KE=1/2v^2
v=sqrt(2*KE/m)
v=sqrt (2*0.03 Joules/(0.02kg))
=1.7 m/s^2
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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: ->->->->->->->->->->->-> :
mass*gravity*displacement=0.03 J
displacement = 0.03 Joules/ (m*g)
=0.03 Joules/ (0.02kg*9.8m/s^2)
displacement =0.15 meters
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&#Very good responses. Let me know if you have questions. &#