Two particles of equal mass moving towards each other with velocities `20 m*s^(-1) and 30 m*s^(-1)` collide. If the collision is elastic, find their velocities after the collision.

Explanation

Two particles are moving towards each other. If the velocity (`u_1)` of one is `20 m*s^(-1)` , then the velocity `(u_2)` of the other particle is `-30 m*s^(-1)`.
After collision, suppose the velocities are `v_1 and v_2` respectively.
From the law of conservation of linear momentum,
`mxx20 -mxx30=mv_1+mv_2`
`or, v_1 +v_2 =-10`
For elastic collision,
`v_2-v_1=u_1-u_2`
or, `v_2-v_1=20-(-30)=50`
solving equation (1) and (2) ,
`v_1=-30m*s^(-1) and v_2=20m*s^(-1)`.