Video: No one should ever have to face the other end of a gun barrel. But if you find yourself in such a situation, let's all hope that it's underwater. Here's our favourite physicist Andreas Wahl proving how the velocity of a bullet slows down like crazy when it's fired underwater with a lovely visual experiment. The bullet nosedives after getting shot and only travels about a metre. If you're more than like 2m away from the rifle, you'd be fine. I'd still want to be at least 10km away from the end of a gun, though.