1. The problem statement, all variables and given/known data The motion of an object is described by the equation x = (0.90 m) cos(PI*t/5). I needed to find: The position of the object at t = 0 and at t = 0.40 s; I got (0.9) and (0.8718) meters, respectively, which were correct. The amplitude (0.9 meters) was also correct. I need to find the frequency (f) of motion. 2. Relevant equations x = (0.90 m) cos(PI*t/5) omega=2(PI)f 3. The attempt at a solution Finding the frequency is the only thing I can't seem to figure out. I tried fiddling with the "cos(PI*t/5)" equation a few ways, but all of my answers are wrong. I think I may be just dividing by the wrong value or something. Could some one give me a head start? Thanks!