Work-energy. help with physics please?

The force is F = mk * weight = �k m g. The energy of the sled K = .5 * m * v0^2. The distance d = K/F = .5 * m * v0^2 / (�k m g) = .5 * v0^2 / (�k g) = 2.7 m. Note that we did not need the mass.