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Question: Answered & Verified by Expert
Assertion : The amplitude of an oscillating pendulum decreases gradually with time.
Reason : The frequency of the pendulum decreases with time.
PhysicsOscillationsAIIMSAIIMS 2003
Options:
  • A if both assertion and reason are true and the reason is the correct explanation of the assertion
  • B if both assertion and reason are true and the reason is not the correct explanation of the assertion
  • C if assertion is true but reason is false
  • D if both assertion and reason are false statements.
Solution:
2172 Upvotes Verified Answer
The correct answer is: if assertion is true but reason is false
The amplitude of an oscillating pendulum decreases with time because of friction due to air. Frequency of simple pendulum is given by
$$
f=\frac{1}{2 \pi} \sqrt{\frac{g}{l}}
$$
which is independent of amplitude and so even though the frequency remains the same, the amplitude keeps on decreasing till it becomes zero.

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