A 64.2-kg skier coasts up a snow-covered hill that makes an angle of 23.8° with the horizontal. The initial speed of the skier is 7.18 m/s. After coasting 1.96 m up the slope, the skier has a speed of 3.13 m/s. Calculate the work done by the kinetic frictional force that acts on the skis.

Answer 1

when up vertically 1.96 sin 23.8
call that h = 1.96 sin 23.8
gain in potential energy = m g h

inital Ke = (1/2) m (7.18)^2 = initial total Energy
final total energy = (1/2)m(3.13)^2+m g h

loss to friction = inital total - final total

= (1/2)m(7.18^2-3.13^2) -mgh

Answer 2

-842.72 J