Question

Sam, whose mass is 75 kg, straps on his skis and starts down a 50-m-high, 20 ^\circ frictionless slope. A strong headwind exerts a horizontal force of 200 N on him as he skies.
a)Find Sam's speed at the bottom using work and energy.
b)Find Sam's speed at the bottom using Newton's laws.
Thanks!

Answer 1

Given data: Mass of the Sam is m-75 kg Angle of the slope, θ-20. Height of the slope, h -50m Length of the slope is sin θ sin 20" a) Speed of the Sam can be determined as follows According to Wrok-energy principle ret Since inti ally starts from rest v 0 The force acting on the skier is the weight of the skier downwards along the slope and the component of wind force along slope (mg sin e- F cos )*d 2(mg sin θ_Fw cos θ)*d 2 M2 2(75kg)(9.8m/s2)sin 20-(200N)cos 20(146.19m) 15.7m/s or)16m/s 15kg (b) Apply Newton laws, the net force on the skier is ma-mg sin θ_Fw cos θ 200N 75kg cos θ-(9.8) sin 20 172 a-g sin θ _ cos 20-0 Using the kinematic equation v-v2adー、2(0.845) (146.19m) = 15.7m/s (or) 16m/s