The diagram below shows snapshots of an oscillator at different times. What is the frequency of the oscillation?

Answer:
0.555 Hz
Explanation:
The period of the oscillation is the time taken for the for the object to return to its original position. (ie. Displacement = 0). From the above snapshot,
Period of oscillation = 1.80s.
From here, finding the frequency is simple as, Frequency = 1/Period. Hence,
Frequency = 1/1.80
= 0.555 Hz (3 sf)