How many hours would make a day if the earth were rotating at such a high speed that the weight of a body on the equator were zero

Options

A. 6.2 h
B. 1.4 h
C. 28 h
D. 5.6 h

Answer

B

Explanation

mg = `mR omega^(2)`
`omega = sqrt((g)/(R)) rArr T = 2pi sqrt((R)/(g)) = 2pi sqrt(64000)`
` = 2pi xx 800 s = (2pi xx 800)/(3600) h = 1.36 = 1.4 `h