You want to use a spring (k=100 N/m) to send a 500-g mass up a frictionless incline (30 degree to horizontal) to arrive at a platform 3m above the ground. How far should you compress the spring?

Answer 1

(1/2) k x^2 = m g h
(1/2)(100) x^2 = (0.5)(9.81)(3)(sin 30)

Answer 2

Since the platform is 3m above ground(vertical height), the gravitational PE gained would be m*g*h - no need to multiply by Sin 30