Q69 / 75 · JEE Main 2025 (29 Jan Shift 1) · Physics
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Time period of a simple pendulum is longer at the top of a mountain than that at the base of the mountain.
Reason (R): Time period of a simple pendulum decreases with increasing value of acceleration due to gravity and vice-versa.
In the light of the above statements, choose the most appropriate answer from the options given below :
- Correct answerABoth \((\mathbf{A})\) and \((\mathbf{R})\) are true and \((\mathbf{R})\) is the correct explanation of \((\mathbf{A})\)
- B(A) is true but (R) is false
- C(A) is false but (R) is true
- DBoth \((\mathbf{A})\) and \((\mathbf{R})\) are true but \((\mathbf{R})\) is not the correct explanation of \((\mathbf{A})\)
Solution
As h increases, g decreases, T increases
$\begin{aligned}
& \mathrm{T}=2 \pi \sqrt{\frac{\ell}{\mathrm{~g}}} \\
& \mathrm{~g}=\frac{\mathrm{g}_0 \mathrm{R}^2}{(\mathrm{R}+\mathrm{h})^2}
\end{aligned}$
Hence, the correct answer is option: 'A'.