Question

Calculate the MI and rotational kinetic energy of a thin uniform rod of mass 10 g and length 60 cm when it rotates about a transverse axis through its centre at 90 rpm.

Answer 1

Data : M = 10 g = 10^-2 kg, L = 60 cm = 0.6 m,

f = 90 rpm = 90/60 Hz = 1.5 Hz

The MI of the rod about a transverse axis through its centre is

Angular speed, ω = 2πf = 2 × 3.142 × 1.5 = 9.426 rad/s

Rotational KE = \(\frac12\)I\(\omega^2\)

= \(\frac12\)(3 x 10^-4) (9.426)²

= 0.01333 j