Universal Gravitation and/or Tidal Forces?

[catphysics]

Homework Statement

The single moon of an Earth-like planet creates tides on the planet that are slowing the planet’s rotation. The planet’s rate of rotation is decreasing at a rate of 7.00 x 10-7 radians/sec/century. The mass of the planet is 6 x 1024 kg, and its diameter is 12,600 km. The radius of the circular orbit of the moon about the planet is 386,000 km. If the moon’s mass is 7.35 x 1022 kg, at what rate is the moon’s distance from the center of the planet increasing? [You may assume that the planet is a uniformly dense sphere.] You must show your work on an attached sheet.

∆r/∆t= __________________ km/year

Homework Equations

I know we will need the universal gravitation equation. possibly, tidal force equations. Can anyone attempt this?

The Attempt at a Solution

 

[member 553083]

I am not sure where to start. I know we will need to use the universal gravitation equation, but I am not sure how. Can anyone help?