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:
Min = 1N
Max = 3N
Avg = 3 + 1 /2 = 2N
How much work is required to stretch the rubber band from 8 cm to 10 cm? W = fnet * ds
W = 2N * .02m
W = .04J
During the stretching process is the tension force in the direction of motion or opposite to the direction of motion?
answer/question/discussion:
It is opposing motion
Does the tension force therefore do positive or negative work?
answer/question/discussion:
Tension does negative work similar to friction. If the force goes against motion it will be -
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 = 2N * .08m
W = .16J
The force is exerted only through the.02 m required to return the rubber band to its unstretched state. Otherwise your work is correct.
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:
W = Fnet *ds
W = 1N * .08m
W= Ke = .08J
At this point how fast will the domino be moving?
answer/question/discussion:
Ke = .5mv^2
V = sqrt.08J /.5 * .02kg
Vf = 2.8m/s
F= ma
A = 1N /.02kg
A = 50m/s^2
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15min
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Very good overall. You missed a couple of details (e.g, the average force is (3 N + 0 N) / 2 = 1.5 N; the force starts out at 0 N, not at 1 N). Be sure to see the link below and let me know if you have questions; revision is optional.
&#At least part of your solution does not agree with the solution and comments given at the link below. You should view the solution at that link and self-critique as indicated there.
Solution
This link also expands on these topics and alerts you to many of the common errors made by students in the first part of this course. &#