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

Options

A. `96` hrs
B. `48` hrs
C. `6` hrs
D. `1.5` hrs

Answer

D

Explanation

By conservation of angular momentum
`I_(1)omega_(1)=I_(2)omega_(2)`
`implies(2)/(5)MR^(2)(2pi)/(T)=(2)/(5)M((R)/(4))^(2)(2pi)/(T)`
`T=(T)/(16)=(24)/(16)=1.5` hrs