Conservation of Momentum
Consider two objects that "interact" or collide or have some effect on each other:
From Newton's Third Law of motion, we know
F12 = - F21 In terms of momentum, this means
F12 = dp1/dt F21 = dp2/dt
so that
dp1/dt = - dp2/dt or
dp1/dt + dp2/dt = 0 d ( p1 + p2) /dt = 0
dpTot/dt = 0
where
pTot = p1 + p2 That is, the total momentum of the system remains constant. This is Conservation of Momentum
Conservation of Momentum is essentially a restatement of Newton's Third Law of Motion.
Linear Momentum Impulse Return to ToC, Ch9, Linear Momentum (c) Doug Davis, 2001; all rights reserved