Question

A circular disc of mass 10 kg is is suspended by a wire attached to its centre. The wire is twisted by rotating the disc and released. The period of torsional pendulum is found to be 1.5 s . Determine the torsional spring constant of wire. ( question no. 21) .....plz solve fast it's urgent!!

Answer 1

Mass of the circular disc, m = 10 kg

Radius of the disc, r = 15 cm = 0.15 m

The torsional oscillations of the disc has a time period, T = 1.5 s

The moment of inertia of the disc is:

I

= × (10) × (0.15)2

= 0.1125 kg m2

Time period,

α is the torsional constant.





= 1.972 Nm/rad

Hence, the torsional spring constant of the wire is 1.972 Nm rad–1.