A 3.9 g mass is released from rest at C which has a height of 0.9 m above the base of a loop-the-loop and a radius of 0.4 m.

Question

The acceleration of gravity is 9.8 m/s^2. Find the normal force pressing on the track at A, where A is at the same level as the center
of the loop.
Answer in units of N.

b. Consider a different situation when the initial height atC has not yet been specified. What is the minimum kinetic energy of the block at B, which is located at the top of the
loop, so that the block can pass by this point without falling off from the track?
Answer in units of J.