Derive Newton's third law of motion from law of conservation of momentum. Share with your friends Share 11 Govind answered this Consider an isolated system in which two bodies A and B collide. Let F1→ be the force exertedby the body A on B for time ∆t. Let F→2 be the force exerted by body B on A for time ∆t.Now, change in linear momentum=Force×timeChange in linear momentum of B=F1→×∆tChange in linear momentum of A=F2→×∆tTotal change in linear momentum of A and B=F→1×∆t+F2→×∆tAs no external force acting on the system, therefore according to newton's second law of motion, the total change in linear momentum of the system is zero.F1→∆t+F→2∆t=0⇒F1→∆t=-F2→∆t⇒F1→=-F2→ 36 View Full Answer