The US Navy's Giant New Electric Railgun

Navy is ready to put an electric gun into shipboard testing at sea. Railguns are weapons that use electricity to fire projectiles at very high energies. The U.S. military is interested in them because they operate without the need to have big piles of explosives lying around, and the projectiles themselves have so much kinetic energy behind them that they don't need to be explosive, either: in just 10 milliseconds, the Navy's railgun prototype accelerates projectiles to between Mach 6 and Mach 7 (8,500 kilometers per hour) with 32 MJ of energy, resulting in a range of just over 200 kilometers. This far surpasses conventional naval weapons.