I have tried this question but I seem not to be getting any where. Qn; An ice-hockey puck is struck from one end of a rink of length 27 m towards the other end. The initial speed is 6m/s, and the puck rebounds from the boundary fence at the other end with a speed which is 0.75 times the speed with which it struck the fence, before just returning to the starting point. Calculate the coefficient of friction between the puck and the ice. My attempt: I applied Newtons second law at instant of collision with fence to get force from rate of change in momentum. this is in terms of mass m and time t, ie 0.25m/t. Equating this force to frictional force gives the coefficient in terms of t after m cancels out.. Applyinng SUVAT seems not to get me anywhere near to geting the time t for the puck to travel 27m, nor the time of impact.