# Homework Help: 51% Efficiency of projectile?

1. Jul 23, 2010

### donkeycopter

Hi,

I have a rubber bouncy ball which is shot off a ramp using a rubber band slingshot.

I've calculated the ideal range, and then measured the real range. By dividing the real by ideal and multiplying by 100, I get a 51% efficiency.

Does that sound viable?

How else can I measure the efficiency of the device?

Thanks!

2. Jul 23, 2010

### rock.freak667

Yes. Since you measured your range, you can work sort of find an ideal situation (one without air resistance) to give you the value you measured. So it works out the same as you did it.

$$Range = \frac{v^2sin2\theta}{g}$$

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