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course Phy 121
10:35 pm July 1
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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:
At 10 cm the maximum tension of 3 Newtons. I think that the minimum tension would be around 0 Newtons. The average tension: 0 + 3= 3/2= 1.5 Newtons
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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:
Because average force is 1.5 N, it would take .03 Joules to stretch the rubber band.
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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:
KE = 1/2 mv^2
1.5 N * .02 m = 1/2 * .02 kg * v^2
.03 J = 1/2 * .02 kg * v^2
.06 J = .02 kg * v^2
+-sqrt. ( 3 m^2/s^2 ) = v
+ sqrt. ( 3 m^2/s^2 ) = v
v = 1.73 m/s
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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:
0 = 1.73 - 9.80t
-1.73 = -9.8 t
.1765 s= t
t = .177 s
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Your instructor is trying to gauge the typical time spent by students on these questions. Please answer the following question as accurately as you can, understanding that your answer will be used only for the stated purpose and has no bearing on your grades:
Approximately how much time did you spend on this question?
25 minutes
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&#Your work looks good. Let me know if you have any questions. &#