# Tennis ball gun, muzzle velocity

1. Dec 6, 2015

### Gavinp

I am designing a tennis ball gun and am trying to work out the forces involved. It is essentially elastic powered but at this stage all I need to know at this stage is this: with the gun at a 20 degree incline what muzzle velocity would result in the ball travelling 50 metres?

2. Dec 6, 2015

### Staff: Mentor

Are you familiar with the SUVAT equations?

3. Dec 7, 2015

### Gavinp

Sorry for delay, but no, however will google them after this reply, thanks for lead. My problem is this, I think I have a viable design for imparting a fair amount of velocity to the ball. It uses a dense coil of catapult elastic which is stretched using a geared crank. releasing the coil propels the ball via a bellows type arrangement which in effect is a large caliber pea-shooter. I want to estimate the range of the design as it stands to see if it will reach the minimum 50m range. To do this I guess I need to find muzzle velocity and then find the amount of energy needed to accelerate the ball to that velocity. Then I need to figure out the amount of energy that can be stored by the elastic. I am hoping the quantity of elastic in the design is sufficient to acheive the range. Any further hints welcome.

4. Dec 7, 2015

### Staff: Mentor

It looks like you have the right idea.