Projectile Motion assignment - Building a projectile launcher

[Hans]

I need help/advice on building a simple projectile launcher, for a tennis ball or smaller object.

I need to calculate the angle so it must be something that shoots fairly straight (ballista?).

Any links or advice on this would be much appreciated

~Hans

[Astronuc]

One could search Google with "ballista".

Is the device supposed to be mechanical, e.g. spring (bow) or lever (catapault, trebuchet)?

The alternative would be a propellant such as compressed gas or explosive chemcial reaction (which is hazardous).

[andrevdh]

Use a vacuum cleaner connected to the front of a long PVC pipe. The pipe from the vc connets via a T piece to the barrel that launches the ball. Seal the front of the pipe with a piece of paper and insert the ball in the other end. The vc will then create a low pressure in front of the ball when it is inserted at the other end. Air pressure then pushes it along the barrel (although I like to think that it is carried along by the air stream). The ball will fly pass the section where the vacuum cleaner is connected to the pipe and push the piece of paper out of the way. With a setup like this one might introduce some spin on the ball as it passes through the barrel. This will then cause it to deflect a bit (usually downwards) due to the Magnus force.

[Penguin10]

I don't know about you, but I'm probably building a trebuchet. One, because they are supposedly very accurate. Two, I can't find anything else on the Internet. Three, the air launcher would take too much time to set up in between launches. Four, I don't think my teacher would appreciate it if I brought a vacuum cleaner into class.