An 18-foot ladder leans against a 12-foot vertical wall, its top extending over the wall. The bottom

Question:

An 18-foot ladder leans against a 12-foot vertical wall, its top extending over the wall. The bottom end of the ladder is pulled along the ground away from the wall at 2 feet per second.
(a) Find the vertical velocity of the top end when the ladder makes an angle of 60° with the ground.
(b) Find the vertical acceleration at the same instant.