This is something I read recently e / Example 5. Momentum and kinetic energy in firing a rifle example 6 The rifle and bullet have zero momentum and zero kinetic energy to start with. When the trigger is pulled, the bullet gains some momentum in the forward direction, but this is canceled by the rifle’s backward momentum, so the total momentum is still zero. The kinetic energies of the gun and bullet are both positive numbers, however, and do not cancel. The total kinetic energy is allowed to increase, because both objects’ kinetic energies are destined to be dissipated as heat—the gun’s “backward” kinetic energy does not refrigerate the shooter’s shoulder! Wrong ( in my opinion)>>>>>The single explosion in the bullet creates a symetrical sphere of force which then expands outward (the opposite of gravity) like a shock wave. The bullet travels faster due to it's smaller mass, it's easier to push, or put another way it offers less resistance to the force. The mass of the Gun + person > bullet. This force I described, what is it? The force that is created from the explosion that is, not the explosion itself. I think a shock wave travels faster than the expansion of gases. I thought it was kinetic energy but I don't see it in this example from "conceptual physics" page 45 by Benjamin Crowell Newtons third law doesn't explain this. It looks to me like the action is the explosion then there are two reactions. We can create this spherical force when we strike a nail with a hammer or light a firecracker or 2 billiard balls. This example 5 just isn't logical... It looks like they overthink it.....This is why I'm nuts... Help me Stimpy!