NECO 2000 Physics · Question 35

In a simple pendulum experiment, a boy observed that the times for 30 oscillations are 70.0s, 72.0s and 67.0s…

Question

In a simple pendulum experiment, a boy observed that the times for 30 oscillations are 70.0s, 72.0s and 67.0s respectively. Calculate the mean period of oscillation of the pendulum.

A.0.14s
B.0.43s
C.2.32s
D.2.40s
E.6.97s

Answer: C. 2.32s

Explanation written with AI and checked against the answer key

Analyze the question: We are given the times for 30 oscillations in three trials. We need the mean period, which is the time for one oscillation. Concept: Period (T) = time taken ÷ number of oscillations The mean period is found by averaging the three times first, then dividing by the number of oscillations. Solution: Step 1: Find the mean time for 30 oscillations. Mean time = (70.0 + 72.0 + 67.0) ÷ 3 = 209.0 ÷ 3 = 69.67 s Step 2: Divide by the number of oscillations. T = 69.67 ÷ 30 = 2.32 s Check against the options: 2.32 s matches option C. (Option E, 6.97 s, comes from dividing by 10 instead of 30, and option D, 2.40 s, is just the period from the 72.0 s trial. Be careful with these traps.) Tip: In pendulum questions, always check the number of oscillations given in the question (here 30) and divide by that. Averaging the times first, then dividing, gives the same result as finding each period and averaging, so use whichever is faster.

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