The earth (mass = `6 xx 10^(24)` kg) revolves round the sun with angular velocity `2 xx 10^(–7 )`rad/s in a circular orbit of radius `1.5 xx 10^(8)` km. The force exerted by the sun on the earth in newtons, is

Options

A. zero
B. `18 xx 10^(25)`
C. `27 xx 10^(39)`
D. `36 xx 10^(21)`

Answer

D

Explanation

Gravitational force exerted by the sun on the earth will provide the required centripetal force.
`F = mRomega^(2)`
`= 6 xx 10^(24)xx (1.5 xx 10^(11)) (2 xx 10^(-7))^(2)`
`= 36 xx 10^(21) N`