Question

if two balls of equal masses are moving towards each other with the same velocity what is the total momentum of the system

Answer 1

let the masses of two bodies be m
velocity of both bodies be v
total momentum of system is mv+mv
= 2mv

Answer 2

we know that momentum is represented by mass *velocity.
so if the two balls contains the same mass and velocity. that can be written as mv+mv
=2mv