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MHT CET · Physics · Oscillations

The force constant of an oscillating simple pendulum is

  1. A Independent of mass of the bob as well as length of the pendulum
  2. B Inversely proportional to mass of the bob and length of the pendulum
  3. C Directly proportional to the mass of the bob
  4. D Directly proportional to length of the bob
Verified Solution

Answer & Solution

Correct Answer

(C) Directly proportional to the mass of the bob

Step-by-step Solution

Detailed explanation

For a simple pendulum, restoring torque equates the
\(\begin{aligned}
& \tau=-m g L \sin \theta=I \alpha \\
& \Rightarrow \alpha=-\frac{m g L}{m L^2} \sin \theta \approx-\frac{g}{L} \theta \\
& \alpha \approx-\left(\frac{g}{L}\right) \theta \Rightarrow \alpha=-\omega^2 \theta=-\left(\frac{g}{L}\right) \theta
\end{aligned}\)
Force constant of an oscillating simple pendulum is given by \(k=m \omega^2\) \(k \propto m\) and \(k \propto \omega^2=\left(\frac{g}{L}\right)\)

Therefore, force constant of an oscillating simple pendulum is directly proportional to the mass of the bob.