Friction of puck on ice?

Question

In the last few seconds of a hockey game, a player aims a slap shot at the opponent's empty net from a distance of 32.5m.

The coefficient of kinetic friction of rubber on ice is 0.005.

Use 9.80 N/kg for |g| and a puck of mass 0.170 kg to keep accuracy of three significant digits.

Show that the pucks speed hardly changes when friction is low.

Answer 1

the only thing thats gonna slow the puck down is friction. based on the question, you only need to consider friction from the ice (not air resistance etc).

how much the puck slows down depends on how long the friction force is being applied.

how long the friction force is being applied depends on how far it has to go (given: 32.5 m) and how FAST the puck is going (not goven)

therefore, you cant really show how much the speed changes because you dont have enough info.

BUT you can get a deceleration number based on:
F=ma
where
F=friction force = weight x coeff of friction
= 9.80 x 0.170 x 0.005 = 8.33e-3 m/s^2

so 2 seconds (a few seconds = 2) gives a change of:
1.67e-2 m/s

Answer 2

I'm sure the instructor that assigned you this question has an answer, but it won't be the right one. This person knows very little about hockey. A slapshot is airborne for a high percentage of its travel. 32.5 meters would be a shot from about center ice. Any halfway decent shooter would hit the back of the net or the end boards from there and the puck wouldn't touch the ice until it landed on it.