Re: Do Ducks have cavalry?

From: andrew968859 <andrew.157barton_at_DxqzVlebs0SQz3IOId3fJlc7N_GR2vWbwZARSY0e4A--CK-Nn06w3wJbyb1>
Date: Thu, 13 Dec 2007 15:45:56 -0000

Thinking about recoil becomes much simpler when you realise that it's about conservation of momentum. You multiply the mass times the velocity - if a one tonne cannon fires a ten kg ball, the cannon must start moving in the opposite direction at one-hundredth the speed of the ball - this is just Newton's Third Law. Most of the energy from the explosion ends up in the kinetic energy of the ball, some ends up in the kinetic energy of the gun, some is dissipated in heat and noise.

At the moment the projectile leaves a rotational thrower, the thrower's centre of mass must move in the opposite direction to the projectile in a straight line. Because of the way the thrower is constructed, and because the base is heavier than the throwing arm, this results in the arm rotating in one direction and the base rotating by a smaller amount in the opposite direction (it must, because angular momentum is also conserved). Assuming, that is, that the thrower stays in one piece ...

Explosive weapons seem different from others because they generally send their projectiles at higher speeds, so the recoil is more dramatic. They're subject to exactly the same laws of physics as anything else.

Andrew            

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