Answer
(a) simple harmonic,
(b) $6\ ft$
(c) $\pi \sec$
(d) $\frac{1}{\pi}\ Hz$
Work Step by Step
Given $d=6sin(2t)$
(a) the motion is simple harmonic,
(b) the maximum displacement from its rest position is $6\ ft$
(c) the period is $p=\frac{2\pi}{2}=\pi \sec$
(d) the frequency is $f=\frac{1}{p}=\frac{1}{\pi}\ Hz$
