Question

04**. A record skiing speed of 203.1km/h was achieved on a mountain slope inclined downward at 51°. At this speed, the force of friction on the skier (air and sliding friction) balances the pull of gravity along the slope, so that the motion proceeds at a constant velocity. (a) What is the rate at which gravity does work on the skier? Assume that the mass of the skier is 75kg.
(b) What is the rate at which sliding friction does work? Assume that the coefficient of sliding friction μk = 0.03​

Answer 1

Solution given:

Velocity or speed of skiing (V) =203.1KM/HR

=203.1*1000/3600=56.41 m/s

θ=51°

mass(m)=75kg

a)now

Rate of work when gravity works

we have different formula

=m*g*sinθ*v

=75*9.8*sin 51*56.41

=27788.6W

b)Rate of work when gravity doesn't work

we have different formula

=μmgcosθ*v

=0.03*75*9.8*cos51*56.41

=923.1W