(Figure 1)A roller coaster car may be approximated by a block of mass m
. The car, which starts from rest, is released at a height h
above the ground and slides along a frictionless track. The car encounters a loop of radius R
, as shown. Assume that the initial height h
is great enough so that the car never loses contact with the track. Find an expression for the kinetic energy of the car at the top of the loop.