Acceleration in SHM

$a_x = - omega ^2* A *cos( omega * t + phi )$

$(omega)"Angular Velocity"$

$(A)"Amplitude"$

$(t)"Time"$

$(phi)"Phase Angle"$

Reference

Young, Hugh and Freeman, Roger. University Physics With Modern Physics. Addison-Wesley, 2008. 12th Edition, (ISBN-13: 978-0321500625 ISBN-10: 0321500628 ) Pg 426, eq 13.16