The earth is slowing down and as a result the moon is coming nearer to it.
The angular momentum of the earth-moon system is not conserved.

Options

A. If both assertion and reason are true and reason is the true explanation of assertion.
B. If both assertion and reason are reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Answer

A

Explanation

(a) Earth is not slowing down. Angular momentum of earth-moon system is conserved, had it not been so, then Kepler's second law of planetary motion would not have been valid.
Kepler's second law states that
`(dA)/(dt) = (J)/(2m)` = constant
where `(dA)/(dt)` is a real speed, `J` is angular momentum, `m` is mass.
Hence, angular momentum is constant.