CBSE Class 9 Answered

In classical mechanics, momentum  is the product of the mass and velocity of an object (p = mv)

Momentum is a conserved quantity, meaning that the total momentum of any closed system (one not affected by external forces) cannot change

In an isolated system with only two objects, the change in momentum of one object must be equal and opposite to the change in momentum of the other object. Mathematically,

A common problem in physics that requires the use of this fact is the collision of two particles. Since momentum is always conserved, the sum of the momenta before the collision must equal the sum of the momenta after the collision:

where:

u signifies vector velocity before the collision

v signifies vector velocity after the collision.