An Object Is Attached to a Coiled Spring $= 15 \mathrm {~cm}$

An object is attached to a coiled spring. The object is pulled down (negative direction from the rest position) and
then released. Write an equation for the distance of the object from its rest position after t seconds.
-amplitude $= 15 \mathrm {~cm}$ ; period $= 4 \pi$ seconds

A) $\mathrm { d } = - 15 \cos \frac { 1 } { 2 } \mathrm { t }$
B) $\mathrm { d } = - 4 \cos \frac { 2 } { 15 } \mathrm { t }$
C) $\mathrm { d } = - 15 \sin \frac { 1 } { 2 } \pi \mathrm { t }$
D) $\mathrm { d } = - 15 \cos \frac { 1 } { 2 } \pi \mathrm { t }$ An object moves in simple harmonic motion described by the given equation, where t is measured in seconds and d in meters . Find the maximum displacement, the frequency, and the time required for one cycle.