Thread: Work and Force on a rubber band.

I've a test coming up in two days and have realized that i dont have many notes on this. i really only need help in setting up the question, but it would also be very helpful if you could work it through to the answer.

1. A force of 2N will stretch a rubber band 2cm:

A: Assuming that Hooke's law applies, how far will a 4N force stretch the rubber band?

B: How much work does it take to stretch the rubber band this far?

Thanks for any help in advance!

Hooke says F=kx, so the first thing to do is solve for the spring constant: k=1 N/cm. Part (A) should be clear now.

For (B), integrate kx from x=0 to 4. Since k=1, this shouldn't be too difficult.

Note that the force is proportional to the displacement, but oppositely directed, so the equation is actually . So the work will actually be negative, since the stretching occurs against the restoring force.