f(x) = 48sin(6x - pi/9) + 48
We can write this in a slightly differenent manner :
f(x) = 48 sin [ 6 ( x - pi/54) ] + 48
Only the "6" matters....this tells how many periods there are in 2 pi
So....if there are 6 periods in each 2pi sec.......then the period is 2pi / 6 = pi/3 sec = the time for one revolution