A simple pendulum makes 50 oscillations in one minute. Determine its period of oscillation

Analyze the question The pendulum completes 50 oscillations in one minute. We need the period, which is the time taken for one complete oscillation.

Concept Period (T) = total time ÷ number of oscillations

Frequency (f) = number of oscillations ÷ time, and T = 1/f

Solution

• Total time = 1 minute = 60 s
• Number of oscillations = 50

T = 60 / 50 = 1.20 s

Check using frequency: f = 50/60 = 0.833 Hz T = 1/0.833 = 1.20 s

Answer The period is 1.20 s, which is option C.

Note that 0.83 (option B) is the frequency in hertz, not the period. This is a common trap in WASSCE questions.

Exam tip Always convert the time to seconds first. Then remember: Period = time ÷ oscillations. If your answer is less than 1 when the pendulum is slow (fewer than 60 oscillations per minute), you have probably calculated frequency instead of period.