A pendulum consists of a bob hanging by a rod from the ceiling ... ...

  A pendulum consists of a bob hanging by a rod from the ceiling (see figure). The pendulum is pulled to the left and released, so it swings back to its equilibrium position. At the moment the rod is vertical and the bob is moving, how many forces are acting on the bob? image
(A) One: gravity.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in 08. Momentum