Unless otherwise stated, all objects are located near the Earth\'s surface, wher

Question

Unless otherwise stated, all objects are located near the Earth's surface, where g = 9.80 m/s2 . A hockey puck impacts a goalie's plastic mask horizontally at 120 mi/h and rebounds horizontally off the mask at 45 mi/h

Part A.If the puck has a mass of 172 g and it is in contact with the mask for 27 ms , what is the magnitude of the average force that the puck exerts on the mask? Express your answer using two significant figures.

Part B What is the direction of the average force that the puck exerts on the mask?

Part C Assuming that this average force accelerates the goalie (neglect friction with the ice), with what speed will the goalie move, assuming she was at rest initially and has a total mass of 87 kg ? Express your answer using two significant figures.

Explanation / Answer

Change in velocity = 120 + 45 = 165 mi/h = 73.76 m/s

F = m * delta v / delta t = 0.172 kg * [73.76 m/s / 0.027 s] = 470 N

a = F / m = 470 / 87 = 5.40 m/s2

vg = a t = 5.40 * 27 * 10-3= 0.146 m/s

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