Question

A novice skier, starting from rest, slides down a frictionless 35 degree incline whose vertical height is 178 m. How fast (m/s) is she going when she reaches the bottom?

Answer 1

$$KE_i+PE_i=KE_f+PE_f,$$ $$0+PE_i=KE_f+0,$$ $$mgh=\dfrac{1}{2}mv_f^2,$$ $$v_f=\sqrt{2gh}=\sqrt{2\cdot 9.8\ \dfrac{m}{s^2}\cdot178\ m}=59.1\ \dfrac{m}{s}.$$