You are given a set of shm equations. Write them down in a summary sheet. One set w.r.t time and another set w.r.t displacement. Use the right set of equations to solve questions. Before using both set of equations , you inevitably must know period or angular frequency or frequency and amplitude. The equations w.r.t time give rise to some difficulty because you need to know the displacement at the start of timing. The sine equation only serves you well if you start timing at x=0 . In the event you start timing at the extreme ends where x= x. or -x. , you can use cosine equation. This switching may pose difficulty to some. There is another suggestion if you want to stick to sine formula everytime . Find the time taken to reach x from the x=0 , deduct this value from T/4 if timing starts from the right end and add this value to T/4 if the timing starts from the left end. You are get around the equation with some creativity.
