I know momentums definition (p=mv) and how to calculate problems involving it, but there are bits I don't understand.
Take a ball thrown at a wall for instance with mass value (5) and velocity (5). This would mean the total momentum of ball is (25). The wall is attached to the earth so the mass is huge and the wall doesn't move (momentum of (0)). Total momentum in system is now (25). This ball hits a wall and bounces back in the opposite direction.
The ball now has a momentum of (-25) so its moving in the opposite direction from which it started. The wall doesn't 'move' due to its high mass (and undetectable gain in velocity). THe total momentum of the system still has a magnitude of (25) but there has been a change in momentum of (50) for the ball. Where did the extra momentum come from? I would think that the ball would transfer all its momentum to the wall in the collision so it would stop moving (as its its momentum drops to 0) but it actually gains momentum to go in the opposite direction.
Where is this extra momentum coming from? Is it linked to newtons 3rd? But then there is a gain of acceleration...