Question

3. Imagine a moon revolving around a planet. If gravitational effects from the moon slow down the planet's rotation about its own axis, will the orbital radius of the moon increase or decrease in order to conserve the total angular momentum of the planet-moon system? (This is the case with the orbital radius

Answer 1

Gravity created an Earth-side bulge in the moon, slowing down its rotation in the past to create the synchronous rotation and keeping the longer lunar axis toward our world. Recent research suggested that the side of the moon facing Earth was determined by how quickly the lunar rotation slowed. Because the moon lost speed slowly, there was about a two-to-one chance that the Man in the Moon would wind up facing Earth rather than keeping a space-bound view.

angular momentum L $\alpha$ v

velocity v $\alpha$ (1/sqrt(radius))

so, the radius must increase to slow down i.e to decrease the velocity of the planet.

In case of any doubt, please do comment sir.