cq_1_141

Phy 201

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 = 0 Newtons

Maximum Tension = 3 Newtons

Average Tension = 1.5 Newtons

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• How much work is required to stretch the rubber band from 8 cm to 10 cm?

answer/question/discussion: ->->->->->->->->->->->-> :

W = Force * `ds

W = 3 Newtons * .02 m

W = .06 Joules

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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: ->->->->->->->->->->->-> :

Opposite

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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: ->->->->->->->->->->->-> :

W = Force * `ds

W = 3 Newtons * .02 m

W = .06 Joules

#$&*

• 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: ->->->->->->->->->->->-> :

F = m * a

3 Newtons = .02 kg * a

a = 150 m/s/s

vf^2 = v0^2 + 2 * a * `ds

vf^2 = (0 m/s)^2 + 2 * 150 m/s/s * .02 m

vf^2 = 6 m^2/s^2

vf = 2.45 m/s

KE = .5 * m* v^2

KE = .5 * .02 kg * (2.45 m/s)^2

KE = .06 Joules

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• At this point how fast will the domino be moving?

answer/question/discussion: ->->->->->->->->->->->-> :

vf = 2.45 m/s

#$&*

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25 minutes

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