If the radius of the earth becomes half of its present value (mass remaining the same ), the new length of the day would be

Explanation

`I_(1)omega_(1)=I_(2)omega_(2)rArr (2)/(5)MR^(2)xx(2pi)/(T_(1))=(2)/(5)M((R )/(2))^(2)xx(2pi)/(T_(2))`
`T_(2)=(T_(1))/(4) therefore T_(1) = 24 h therefore T_(2)=6 h`.