# Homework Help: Projectile Motion Project

1. Sep 20, 2004

### literati

I need some uinspiration for a physics project concerning projectile motion. Our group needs to design and build a device that will launch an object a considerable distance (say, 50-100 yds), can be adjusted to shoot on an angle or horizontally, and maintains a fairly constant initial velocity. I'm not asking for blueprints, just a couple ideas.
Thanks,
Kate

2. Sep 20, 2004

### arildno

Make a "cannon" with a compressible spring to provide the energy.
As long as you compress the spring equally each time, and makes it hit the ball in the same position, you should impart roughly the same amount of energy (and hence, initial velocity) to it each time.

3. Sep 20, 2004

### faust9

A spring canon will be hard to compress and control for a 150 to 300 ft shot. A compressed air canon would be the best choice IMO. Use an accurate pressure gauge and find a pressure which allows you to fire your projectile 300ft at 30 degrees. You might think 45 degrees would yield the longest distance--that only happens in physics world. Once you find the pressure needed to launch the 300 ft then you can develop tables of angles vs distance. As long as you use the same pressure each time your velocity should be fairly consistent.

Good luck.

4. Sep 20, 2004

### arildno

faust9 is certainly more of a cannon expert than myself!
Just one more thing:
You ought to make your projectile out of a dense material (not a ping pong ball); this in order to reduce the effect of air resistance.