How Can I Build a Cost-Effective Air-Powered Projectile Launcher?

[tinnguyen123]

Homework Statement

i need to built a launcher to shoot anything(no sharp object, bb bullets, or must be bigger then 5mm) out for about 55 Meters...

the only force i can use to launch the "object" is airs that are inside a 2Liter coke bottle...

every other material is ok..

PS: I am not rich...

Homework Equations

The Attempt at a Solution

Cort - alcohol cort to launch.. but doesn't work...

 

[tinnguyen123]

bump...