Question

will the momentum of a system that consists of moving objects and that is subject to a net force of friction be conserved​

Answer 1

Answer:

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Answer 2

Answer:

There is a very useful property of isolated systems, total momentum is conserved.

Lets use a practical example to show why this is the case, let us consider two billiard balls moving towards each other. Here is a sketch (not to scale):

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When they come into contact, ball 1 exerts a contact force on the ball 2, F⃗ B1, and the ball 2 exerts a force on ball 1, F⃗ B2. We also know that the force will result in a change in momentum:

F⃗ net=Δp⃗ Δt

We also know from Newton's third law that:

F⃗ B1Δp⃗ B1ΔtΔp⃗ B1Δp⃗ B1+Δp⃗ B2=−F⃗ B2=−Δp⃗ B2Δt=−Δp⃗ B2=0

This says that if you add up all the changes in momentum for an isolated system the net result will be zero. If we add up all the momenta in the system the total momentum won't change because the net change is zero. Important: note that this is because the forces are internal forces and Newton's third law applies. An external force would not necessarily allow momentum to be conserved.

In the absence of an external force acting on a system, momentum is conserved.

Explanation: