A buoy floating in the sea is bobbing in simple harmonic motion with period 3 seconds and amplitude 12 in. Its displacement d from sea level at time t = 0 seconds is -12 in, and initially it moves upward. (Note that upward is the positive direction.) Give the equation modeling the displacement d as a function of time t

A buoy floating in the sea is bobbing in simple harmonic motion with period 3 seconds and amplitude 12 in. Its displacement d from sea level at time t = 0 seconds is -12 in, and initially it moves upward. (Note that upward is the positive direction.) Give the equation modeling the displacement d as a function of time t