Entering the right door!
When you tackle questions on gravitation , do no enter by main door ( gravitational force). Always use a side door , the use of gravitational field strength.
When you handle energy , always use gravitational potential rather than gravitational potential energy.
Gravitational field strength and potential are quantities in per unit mass. Similar to knowing the price per kg of product is very useful when purchasing a product. Or liken to knowing the strength of a drug (per unit mass) so that it can be administered correctly to persons of different masses.
