Why is linear momentum conserved?
A particle of mass “m” moving at velocity “v” has a linear momentum of . Two basic particles having the same speed v approaching each other for a “head-on” collision (i.e., where the velocities are parallel to the line determined by the particle centers) have a momentum of since the momenta are equal and opposite. After impact the velocities are reversed so that the sum of their momentum is . Thus, linear momentum is conserved during this collision. If two particles approaching a head-on collision with unequal velocities and , say in the same direction, have a momentum . If these particles are viewed from a frame moving at velocity in the same direction as and then particle 1 will be seen to have a velocity while particle 2 will be seen to have a velocity opposite that of particle 1 . Thus, in this frame of reference the particles are approaching with equal and opposite velocities. During collision the velocities are simply reversed, particle 1 has velocity and in this moving frame par
