A small ball of mass `m` collides with as rough wal having coeficient of friction `mu` at an angle `theta` with the normal to the wall. If after collision the ball moves wilth angle `alpha` with the normal to the wall and the coefficient of restitution is `e`, then find the reflected velocity `v` of the ball just after collision.

Explanation

`mvcosalpha-[m(-ucostheta)]=intNdt`
`mvsinalpha-musintheta=-muint Ndt`
`and e=(vcosalpha)/(ucostheta)impliesvcosalpha=eucostheta`……….i
`or mvsinalpha-musintheta-mu(mvcosalpha+mucostheta)`……….ii
`From eqn i and ii v=u/(sinalpha)[sintheta-mucostheta(e+1)]`