A 0.105-kg hockey puck moving at 24 m/s is caught and held by a 75-kg goalie at rest. With what speed does the goalie slide on the ice after catching the puck?

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Answer 1 · 2017-02-14T20:17:43

The goalie slides with a speed of 0.034 m/s after catching the puck. Use conservation of momentum to solve this question.

The momentum of the puck before it is caught:

$p_(puck) = 24 \ m s^-1 times 0.105 \ kg = 2.52\ kg \ m s^-1.$

After catching the puck, all the momentum is transferred to the goalie. Using conservation of momentum:

$Speed \ of \ goalie = (2.52\ kg \ m s^-1)/(75kg + 0.105kg).$

Notice that as the goalie caught the puck, their combined mass is used for the final momentum calculation.

$Speed \ of \ goalie = (2.52\ kg \ m s^-1)/(75.105 \ kg).$

$Speed \ of \ goalie ~= 0.034 \ m s^-1.$

The goalie slides with a speed of 0.034 m/s after catching the puck.