Solution
x(t)= (6.0m) cos( 3?t + ?/3)
xm=6.0m, ?=3? rads/s, ? =?/3 rads (constants!)
(a) x(t=2) = 6cos(6?+ ?/3)=6cos(600)=3.0m
(b) v(t)= -(3?)(6)sin(3?t + ?/3) v(t=2)=-18?sin(6?+?/3)=-18?31/2/2 m/s
(c) a(t) = - (3?)2(6) cos( 3?t + ?/3) a(t=2)= -54 ?2cos(600)= -27 ?2m/s2