# Rubber Bands and Paper Clip

#### BeefyBeef

Hi all. I have a question. How do you show the difference between stress (pressure) and force? We were given 2 short elastic bands, 2 long elastic bands, and 2 paper clips. Idea that came up was to tie one elastic band to 1 weight (anything). Suspend it. And measure length of elastic band. Then take 2 same length elastic bands and tie them both to wait suspending the same weight with the elastic bands side by side. Then measure the length of the elastic bands.

Obviously, the parallel suspension will have shorter length. This goes to show that the two elastic bands have twice as much cross sectional area if you dice the elastic bands than the experiment with only 1 elastic band. I understand that pressure is the amount of force per unit area. However, I don't see how this connects to showing the difference between stress and force? How do I show it? If i can't with this experiment. What other experiment can I do?

And the other experiment is to show the differcence between strain and deflection. This one. I blanked out. Thoughtless. No idea. All I know is that strain is change in length over the original length. Plz Help. Thx.

peace

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#### russ_watters

Mentor
You seem to understand the concepts, but I'm not sure what you mean by "show" it.

It isn't easy to measure the cross sectional area, but typically there is a direct relationship between length and cross sectional area. Double the length and you cut the cross sectional area in half.

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