1. The problem statement, all variables and given/known data A mass oscillating in SHM starts at x=A and has a period of T. At what time, as a fraction of T, does it first pass through x=0? 2. Relevant equations x(t) = Acos(wt + [tex]\varphi[/tex]) 3. The attempt at a solution I'm not sure if this means I set x(t) = A, or if the [tex]\varphi[/tex] = -A? Also, does it use A because I'm supposed to recognize that it's equal to amplitude and do something about it (i.e. cancel)? Not too sure how to go about doing this though...any hints?