phy 121
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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: ->->->->->->->->->->->-> :
the minimum is 0 Newtons and the max is 3 Newtons.
• 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: ->->->->->->->->->->->-> :
3 Newtons
• 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: ->->->->->->->->->->->-> :
`dW = Fnet * `ds
`dW = 3 Newtons * 2cm
`dW = 3 Newtons * .02m
`dW = .06 Joules
1/2mv^2
½ (.02 kg) (v^2) = .06 Joules
½ / ½ (.02kg) (v^2) = .06 Joules / ½
.02kg / .02kg (v^2) = .12 Joules / .02kg
V^2 = 6 m^2/s^2
V = 2.45 m/s
• If instead the rubber band is used to 'shoot' the domino straight upward, then how high will it rise?
answer/question/discussion: ->->->->->->->->->->->-> :
`dW = Fnet * `ds
.06 Joules = 3 Newtons * `ds
.06 Joules / 3 Newtons = 3 Newtons / 3 Newtons * `ds
`ds = .02 meters
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30 min
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you got double the PE you should have; otherwise fine. Check the link:
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Solution
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