## Question:

A ball is thrown onto a rough floor at an angle of θ. If it rebounds at the same angle φ , determine the coefficient of kinetic friction between the floor and the ball. The coefficient of restitution is e. Hint: Show that during impact, the average impulses in the x and y directions are related by ${ I }_{ x }$ = μ${ I }_{ y }$. Since the time of impact is the same, ${ F }_{ x }$Δt = μ${ F }_{ y }$Δt or ${ F }_{ x }$ = μ${ F }_{ y }$.