Frictional force on a skier

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Quandaries & Queries

Question from William, a student:

An olympic skier moving at 20.0 m/s down a 30 degree slope encounters a region of wet snow and slides 145m before coming to a halt. What is the coefficient of friction between the skis and the snow?

My strategy was to use work/kinetic energy formula (FdCosO=1/2MV^2-1/2MV^2) to find the frictional force. Then plug that result into Mk=Ff/Fn to get the coefficient of friction. The problem is that I don't know the mass of the skier!

Hi William.

It sounds like that strategy should work. Note that F_f/F_n = k, not Mk. Mass cancels out since M appears inside both F_f and F_n.

Stephen La Rocque.>

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