physics
posted by chelsie .
Find the acceleration down the ramp:
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.

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