Q.

If the radius of earth is reduced to three-fourth of its present value without change in its mass then value of duration of the day of earth will be _______ hours 30 minutes.         [2024]


Ans.

(13)     By angular momentum conservation, I1ω1=I2ω2

            25mr2·ω=25m34r2·ω'ω'=169ω

            2πT'=169×2πTT'=9T16=916×24hours=9×32hours

            T'=272hr=13 hr 30 mins