Suppose the earth suddenly expends and its radius become 2R (R = radius of earth) keeping its mass same, then that will be the length of the day which at present is of 24 hours?

Options

A. 1.5 hr
B. 6 hr
C. 96 hr
D. 36 hr

Answer

C

Explanation

Here, `L_(1)=L_(2)`
`I_(1)W_(1)=I_(2)W_(2)`
`therefore (2)/(5)MR_(1)^(2)W_(1)=(2)/(5)MR_(2)^(2)W_(2)`
`therefore R_(1)^(2)xx(2pi)/(T_(1))=R_(2)^(2)xx(2pi)/(T_(2))`
`therefore (R_(1)^(2))/(T_(1))=((2R_(1))^(2))/(T_(2))`
`therefore (1)/(24)=(4)/(T_(2))`
`therefore T_(2)=96hr`