# Tension Forces and rubber bands

1. Oct 4, 2006

### NIZBIT

I am doing some work with tension forces and applying different masses to different items like strings. We did some things with rubber bands too. I am having trouble with one of the questions posed.

"In general, in order for a rubber band to pull back, what does it have to do?"

I want to say there is nothing the rubber band could do. It was made that way. So I guess they're asking that if the tension of the rubber band increased it would pull back more? Or that for a rubber band to pull back it must be strecthed?

2. Oct 4, 2006

A rubber band behaves elastic up to some point.

3. Oct 4, 2006

### NIZBIT

This has me stumped:

"What change takes place in a surface so it can push back?"

4. Oct 5, 2006

### andrevdh

When a force displaces an object through a certain distance energy is expended by the person/machine or whatever exerts the force. Usually internal energy is converted to mechanical energy with such a process. We find the same situation when an eleastic is stretched - it needs to convert internal energy to mechanical energy in order to pull back on whatever is extending it. You can actually notice such a temperature increase of an elastic as a result of such a process. Try to feel the difference in temperature of an elastic on your lips before and after stretching it.