Cannon~

A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellants to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower. (if you are interest in details of cannon;s function, and structure. please go to google.com and simply type cannon inside.)  but how can the cannon fire the heavy gun powers to a few kilometers away? well, that is the magic of physics.
and the most exciting thing is, we are actually building a cannon in our physic class, of course a mini mode.

here are some pictures of a cannon.