Answer
The speed of the body is greatest when:
(b) The body is at the equilibrium point.
Work Step by Step
Initially, the only force acting on the mass is gravity since the spring is in its relaxed position. The mass starts with a speed of zero but a maximum acceleration downward.
When the mass reaches the equilibrium position, the upward force exerted by the spring is equal in magnitude to the weight. Then the net force is zero so the acceleration is zero. At this point the mass has reached maximum speed.
After passing the equilibrium point, there is a net force directed back toward the equilibrium point which slows down the mass.
The speed of the body is greatest when:
(b) The body is at the equilibrium point.
