Q. If the earth shrinks such that its mass does not change but radius decreases to one quarter of its original value then one complete day will take
A) 96 h
B) 48 h
C) 6 h
D) 1.5 h
Explanation
(d) We know that angular momentum of spin $= I\omega$
By the conservation of angular momentum
$\frac{2}{5}MR^{2}.\frac{2\pi}{T} = \frac{2}{5}M\left( \frac{R}{4} \right)^{2}.\frac{2\pi}{T^{'}}$
$T^{'} = \frac{T}{16} = \frac{24}{16} = 1.5$h
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.