A block is first placed on its long side and then on its short side on the same inclined plane, as shown. The block slides down the plane on its short side but *** at rest on its long side. A possible explanation is:
A. the short side is smoother
B. the frictional force is less because the contact area is less
C. the center of gravity is higher in the second case
D. the normal force is less in the second case
E. the force of gravity is more nearly down the plane in the second case
