posted by sand .
A body of mass 5.0kg slides from rest down a plane inclined at 30degrees to the horizontal. After sliding 12m down the plane it is found to have a speed of 10m/s.
a) How much work has been done in overcoming friction along the plane?
b) Calculate the average value of the force of friction.
Try using conservation of energy.
Work done against friction = PE loss - KE gain
W = M*g*(12 sin30) - (M/2)(10^2)
= 44 J
Average friction force = W/12 m = 3.67 N