posted by cbrown .
A hockey puck of mass 0.27 kg is sliding along a slippery frozen lake, with an initial speed of 56 m/s. The coefficient of friction between the ice and the puck is μK = 0.032. Friction eventually causes the puck to slide to a stop. Find the work done by friction.
The work done by friction is -(1/2) M V^2, no matter what the coefficient of firction is. With a + sign, it is the work that the puck does against friction, which equals the initial kinetic energy.
If you compute the friction force and multiply it by the distance the puck slides before stopping, to get the work done, you will find that ìK cancels out.