90 mph is almost nothing.

To help you understand, think about tossing a bullet back and forth with a friend. You can do that without your hand getting hurt at all, because the bullet is not going very fast. However, that same bullet being shot from a gun is going very fast coming out of barrel, and it hitting your hand at that speed makes a very significant difference for how it would affect your hand if the bullet hit your hand.

And the speed of a bullet out of a gun is practically nothing compared with going near the speed of light; the forces involved are vastly greater with vastly greater speed.