일반물리학 1 — Rolling, Torque, and Angular Momentum: Problem 12

12 In Fig. 11-28, a solid brass ball of mass 0.320 g will roll smoothly along a loop-the-loop track when released from rest along the straight section. The circular loop has radius $R = 12.0\text{ cm}$, and the ball has radius $r \ll R$. (a) What is $h$ if the ball is on the verge of leaving the track when it reaches the top of the loop? If the ball is released at height $h = 6.00R$, what are the (b) magnitude and (c) direction of the horizontal force component acting on the ball at point Q?