An 80-M Massless Rod Is Loosely Pinned to a Frictionless Pivot

Multiple Choice

An 8.0-m massless rod is loosely pinned to a frictionless pivot at 0, as shown in the figure. A very small 4.0-kg ball is attached to the other end of the rod. The ball is held at A, where the rod makes a 30° angle above the horizontal, and is released. The ball-rod assembly then swings freely with negligible friction in a vertical circle between A and B. The tension in the rod when the ball passes through the lowest point at D is closest to

A) 160 N.
B) 200 N.
C) 120 N.
D) 80 N.
E) 40 N.