Meriam, Kraige & Bolton — Kinetics of Particles: Problem 3_94

3/94 The collar of mass $m$ is released from rest while in position $A$ and subsequently travels with negligible friction along the vertical-plane circular guide. Determine the normal force (magnitude and direction) exerted by the guide on the collar (a) just before the collar passes point $B$, (b) just after the collar passes point $B$ (i.e., the collar is now on the curved portion of the guide), (c) as the collar passes point $C$, and (d) just before the collar passes point $D$. Use the values $m = 0.4 \text{ kg}$, $R = 1.2 \text{ m}$, and $k = 200 \text{ N/m}$. The unstretched length of the spring is $0.8R$.