I don't know if this is a repost or not but i thought it was cool and worth posting. It's the the navy's new rail gun prototype that they claim can shoot a 40 pound projectile over 100 miles at Mach 7 (about 5,600 MPH)
[youtube_browser]-uV1SbEuzFU[/youtube_browser]
[youtube_browser]-uV1SbEuzFU[/youtube_browser]