Find the acceleration down the ramp:

Question

skateboarder starts from rest at the top of a 12.5 m slick ramp that makes a 25 degree angle with the horizontal. (coefficient of rolling friction is negligible). Combined mass of skateboarder and skateboard = 75 kg.

Answer 1

Net force down= mass*a
mg*SinTheta=m*a solve for a.
If you had friction, it would be like this:
mg*sinTheta-mu*mg*CosTheta=ma