In the figure here, a solid brass ball of mass 0.306 g will roll smoothly along a loop-the-loop track when released from rest along the straight section. The circular loop has radius R = 0.18 m, and the ball has radius r << R.
(a) What is h if the ball is on the verge of leaving the track when it reaches the top of the loop?
(b) If the ball is released at height h = 4R, what is the magnitude of the horizontal force component acting on the ball at point Q?