Show that law of conservation of linear momentum and Newton's third law are the same

Asked by shobhit_dc | 18th Jan, 2012, 07:23: PM

Expert Answer:

According to the third law of motion, Action reaction forces are equal and the total external force on the system being zero , momentum is conserved.
F1 = F2
ma1 = ma2
mdv1/dt = mdv2/dt
dmv1/dt = dmv2/dt
dp1/dt = dp2/dt
integrating with time dt gives,
p1 = p2
Consider a collision between two bodies. Since they exert equal and opposite forces on each other for the same time, they produce equal and opposite changes in momentum in each other--thus the total momentum of the system remains unchanged.

Answered by  | 19th Jan, 2012, 10:38: AM

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