Two different unknown masses A and B collide. A is initially at rest when B has a speed v. After collision B has a speed v/2 and moves at right angles to its original direction of motion. Find the direction in which A moves after collision.

Explanation

Momentum along horizontal:
`mv+0=v_(2)costheta_(2)" "...(1)`
Momentum along vertical:
`m(v//2)=v_(2)sintheta_(2)" "...(2)`
`((2))/((1))impliestantheta_(2)=(1)/(2)`
Direction is given by
`theta_(2)=tan^(-1)((1)/(2))=26^(@)56'`