A buoy floating in the ocean is bobbing in simple harmonic

Last updated: 7/13/2022

A buoy floating in the ocean is bobbing in simple harmonic motion with amplitude 4 ft and period 7 seconds. Its displacement d from sea level at time 1 = 0 seconds is 0 ft, 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.