Question

If polar ice caps melt, then the time duration of one day

• A. increase
• B. decreases
• C. does not change
• D. zero

Answer 1

Answer: (A)

increase

Answer 2

Melting polar ice causes water to flow towards the equator, increasing Earth's moment of inertia ($I$) as mass is redistributed farther from the axis of rotation. By the law of conservation of angular momentum ($I\omega = \text{constant}$), an increase in $I$ leads to a decrease in angular velocity ($\omega$). The time duration of one day is the period of rotation ($T = \frac{2\pi}{\omega}$). Therefore, a decrease in $\omega$ results in an increase in $T$.