Seed Question 151

course Phy 231

June 294:07 pm

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:

F = kx

3 = k*.1

k = 30

F = kx

F = 30*.08

F = 2.4

The max tension is given at 3N, the minimum tension is 2.4N.

• 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:

If the system is conservative, the potential energy would be equal to the total work done. Calculating the total work, we get W = F*d = 3*10 = 30J. That means the elastic potential energy would be 30J at 10cm.

• 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:

K = 1/2 mv^2

30J = 1/2 * .02 v^2

30 = .01v^2

3000 = v^2

v = 54.77 m/s

• If instead the rubber band is used to 'shoot' the domino straight upward, then how high will it rise?

answer/question/discussion:

F = ma

3 = .02*a

a = 150

U = mgh

30J = .02*150*h

30 = 3h

h = 10 m

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See also my notes on the preceding 'seed' question. You've repeated the error of the preceding regarding the equilibrium position; and you have some errors in units. But most of your thinking is correct.

Check out the link below:

&#Please compare your solutions with the expanded discussion at the link

Solution

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