A hockey puck impacts a goalie's plastic mask horizontally at122 m/h and rebounds horizontally off the mask at 47mi/h. If the puck has a mass of 170 gram and it is in contact with the mask for 25 milliseconds,
a) Find the average force that the puck exerts on the mask?
b) Suppose that this average force accelerates the goalie (ignore friction with the ice), determine with what speed will the goalie move, suppose she was at rest initially and has a total mass of 85 kilogram?