An object undergoes simple harmonic motion along an x axis w

An object undergoes simple harmonic motion along an x axis with a period of 0.40 s and amplitude of . Its position is = 12 mm when t = 0.

Determine all the possible values of i in the equation of motion. Suppose that <i.

If there is more than one answer enter your answers in ascending order separated by commas.

I got .44 radians and 2.98 radians and it said Term 1 not quite, check through calculations.

Solution

Consider Acos(wt + phi) = x

A = 27mm, w = 2pi/0.40, 27cos(phi) = 12
phi = 63.6122 deg and -63.6122 deg or 1.1096 rad and -1.1096 rad
for sin function, add pi/2 to both -> 2.6796, 0.4604 rad