What is its velocity at a point 12 ft from the top?

Question

A body of mass m Starts down from rest from the top of an inclined plane 20 ft long and 10 ft high. What is its velocity at a point 12 ft from the top?

Answer 1

sinθ = 10/20 = 0.5. So, h = 12sinθ = 6ft

mg(H - h) = mv²/2; v = √2g(H - h) = √2·32ft/s²(10ft - 6ft) = 16 ft/s