This one railgun by the Navy can also fire projectiles, at an out-of-the-barrel speed of Mach 7 (approximately 5,000 miles per hour).
A railgun is powered by electricity, and accelerates a conductive projectile along a pair of metal rails. The current interacts with the magnetic fields generated by the rails and this speeds the projectile on its very fast way.
In case you are wondering, these projectiles have to be specially made in order to prevent them from melting from the air friction. By the way, it takes 33 Megajoules of energy to fire this gun.
