# Homework Help: Why is the efficiency of a rubber band slingshot constant

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1. Mar 3, 2016

### CTHAEH

1. The problem statement, all variables and given/known data
I need to explain for a lab, why the efficiency of a rubber band slingshot constant for different stretch lengths. I don't need math, just a general explanation of why kinetic energy of projectile/elastic potential energy in rubber band is constant.

2. Relevant equations

3. The attempt at a solution

2. Mar 3, 2016

### haruspex

Not sure I can answer it either, in the sense of a reasonable basis for predicting that result.
But it might help to think about the two phases, stretching and releasing. If you were to plot the extension against tension during that cycle, what would you expect?

3. Mar 3, 2016

### CWatters

Perhaps a slingshot is close to ideal? In which case the efficiency is always close to 100%?

4. Mar 3, 2016

### haruspex

Possibly, but in that case one could look at loss, i.e. 1-efficiency, thereby exposing variation better.

5. Mar 3, 2016

### rcgldr

Last edited: Mar 3, 2016