A pendulum oscillates 30 times in 3 seconds. Choose the correct statement from…
2019
A pendulum oscillates 30 times in 3 seconds. Choose the correct statement from among the following:
Answer: B. Its time period is 0.1 s and frequency is 10 Hz. — Concept: Frequency (f) is the number of oscillations completed per second, and time period (T) is the time taken for one complete oscillation. The two are…
- A.
Its time period is 10 s and frequency 3 Hz.
- B.
Its time period is 0.1 s and frequency is 10 Hz.
- C.
Its time period is 10 s and frequency is 0.3 Hz.
- D.
Its time period is 0.3 s and frequency is 0.3 Hz.
Attempted by 2 students.
Show answer & explanation
Correct answer: B
Concept: Frequency (f) is the number of oscillations completed per second, and time period (T) is the time taken for one complete oscillation. The two are reciprocals of each other, so f = n/t, T = 1/f, and their product T x f must equal 1.
Application:
Compute the frequency from the given data: f = number of oscillations / time taken = 30 / 3 = 10 Hz.
Compute the time period as the reciprocal of frequency: T = 1/f = 1/10 = 0.1 s.
Cross-check: Multiply the two computed values: T x f = 0.1 x 10 = 1, confirming they satisfy the reciprocal relationship.
So the pendulum has a time period of 0.1 s and a frequency of 10 Hz.