Question

If most of the population on earth is migrated to poles of earth then the time duration of a day :

• A. Increases
• B. Decreases
• C. Remains same
• D. First increases then decreases

Answer 1

The correct option is B Decreases

External torque is zero.
$\therefore$ Angular momentum is conserved.
$\therefore I_1{\omega }_1=I_2{\omega }_2$
If people migrate towards the pole, most of the mass gets concentrated near the rotational axis of earth due to which moment of inertia decrease due to that Angular velocity will increase. And finally duration of day will $decrease$.
$T=\frac{2\pi }{\omega }$