An object exhibits simple harmonic motion. The position of the object as function of time is:
with $f=60\,Hz$ and $A = 5\,cm$.
Which of the times listed below (units are seconds) are two CONSECUTIVE times when the object's acceleration magnitude is at its maximum value?
Note the magnitude is always positive without regard to the direction of the acceleration. So the question is about the absolute value of the acceleration.
Consecutive times when $\left|a\right|$ is a maximum value.