Question:medium

A simple pendulum has time period \(T_1\). The point of suspension is now moved upward according to the relation \(y = kt^2\) where \(k = 1\) ms\(^{-2}\). The time period now becomes \(T_2\). The ratio \(\frac{T_1^2}{T_2^2}\) is \((g = 10\) m/s\(^2)\)

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Upward acceleration of support increases effective g, decreases time period.
Updated On: Jun 19, 2026
  • 6/5
  • 5/6
  • 1
  • 4/5
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The Correct Option is A

Solution and Explanation

To solve this problem, we need to understand how the upward motion of the suspension point affects the time period of the simple pendulum. The basic time period \(T_1\) of a simple pendulum, when the point of suspension is stationary, is given by the formula:

\(T_1 = 2\pi \sqrt{\frac{L}{g}}\)

where \(L\) is the length of the pendulum and \(g\) is the acceleration due to gravity.

When the point of suspension is accelerating vertically upwards with acceleration \(a = \frac{d^2y}{dt^2} = 2k = 2\text{ m/s}^2\), the effective gravitational acceleration becomes \(g' = g + a\).

So, the modified time period \(T_2\) is given by:

\(T_2 = 2\pi \sqrt{\frac{L}{g + a}}\)

Substituting the given values, \(g = 10\text{ m/s}^2\) and \(a = 2\text{ m/s}^2\), we find:

\(T_2 = 2\pi \sqrt{\frac{L}{10 + 2}} = 2\pi \sqrt{\frac{L}{12}}\)

Thus, the ratio of the squares of the time periods is:

\(\frac{T_1^2}{T_2^2} = \frac{\left(2\pi \sqrt{\frac{L}{10}}\right)^2}{\left(2\pi \sqrt{\frac{L}{12}}\right)^2} = \frac{L/10}{L/12} = \frac{12}{10} = \frac{6}{5}\)

Therefore, the correct option is \(\frac{6}{5}\).

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