Question

Is momentum always conserved?

Answer 1

You could first think of the origin of the concept of conservation of momentum. You could think of all the possible cases where there is a chance of momentum not being conserved. You could also give the mathematical expression for conservation of momentum. Thus, you’ll get the answer.

Complete answer:
Let us recall that the conservation of momentum simply is the statement of Newton’s third law of motion which states that for every action there is a reaction that is equal in magnitude and opposite in direction.
For any collision, forces that act on the colliding bodies are always equal in magnitude and opposite in direction at every instant. For this very reason we could say that the momentum is always conserved.
If you wish to check whether momentum for a collision or any other event, you could simply measure the total mass before and after that particular event and the net velocity before and after the event for every object involved in that event.
We know that product of mass and velocity gives the momentum, so mathematically we could say that,
$Mv=k$
Where, k is some constant.

Note:
In case of inelastic collisions, a loss of kinetic energy occurs. However, momentum is still conserved in these inelastic collisions while kinetic energy is not. Some of the kinetic energy is getting converted into heat, sound or may be deformation of objects in some cases.