According to conservation of momentum, when two objects collide, the momentum lo

Question

According to conservation of momentum, when two objects collide, the momentum lost by one object equals the momentum gained by the other. In a practicum, you derived momentum conservation from newton's 3rd law and other assumptions. Here, we want you to give a common sense , non-mathematical explanation of the connection between newton's 3rd law and momentum conservation.

In other words, make an argument that newtons third law and momentum conservation, though they seem different on the surface, actually say similar things. A good answer will help your room mate understand why those two seemingly-disconected laws are closely connected. Again, we are looking for conceptual , common sense reasoning, not formal mathematical reasoning.

Explanation / Answer

By the conservation of energy we know that if external effects are neglected then the energy remain constant of the system.
Similarly if there is no external force is acting in the system then the momentum is remain conserved.
This is directly linked with the newton's third law.
As we knwo that every reaction has equal and opposite reaction.
Consider two bodies A and B since no external force is acting therefore while collision
both the bodies will apply the equal and opposite force on each other by third law.
Since they will remain in contact for the same time also so we can say that the impulse transfer would be the same and opposite in direction.
Therefore the net change in impulse is Zero.
As we know that impulse is given by the change in momentum.
Since impulse is zero hence the change in momentum is also zero.
therefore momenum will remain conserved.

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