A steel block is attached to a helical spring on a frictionless air track. The block is initially set to a position -A units from its equilibrium position and released from rest. Which graph illustrates the positions of the block at given time: 0, 1/4 T, 1/2 T, 3/4 T, T, and 5/4 T, where T is the natural period of oscillation?

• A.
• B.
• C.
• D.

Answer: (D)