Two masses m and \(\frac{m}{2}\;\)are connected at the two ends of a massless rigid rod of length l. The rod is suspended by a thin wire of torsional constant at the centre of mass of the rod-mass system (see figure). Because of torsional constant k, the restoring torque is τ = kθ for angular displacement θ. If the rod is rotated by θ0 and released, the tension in it when it passes through its mean position will be:

\(\frac{{k\theta _0^2}}{{2l}}\)

Two masses m and \(\frac{m}{2}\;\)are connected at the two ends of a m

1.	Two masses m and \(\frac{m}{2}\;\)are connected at the two ends of a massless rigid rod of length l. The rod is suspended by a thin wire of torsional constant at the centre of mass of the rod-mass system (see figure). Because of torsional constant k, the restoring torque is τ = kθ for angular displacement θ. If the rod is rotated by θ0 and released, the tension in it when it passes through its mean position will be:
A.	\(\frac{{3k\theta _0^2}}{l}\)
B.	\(\frac{{2k\theta _0^2}}{l}\)
C.	\(\frac{{k\theta _0^2}}{l}\)
D.	\(\frac{{k\theta _0^2}}{{2l}}\)
Answer» D. \(\frac{{k\theta _0^2}}{{2l}}\)