Step-by-step explanation:
1. Gravitational attraction
Gravitational attraction is a force for an object that acts on the level surface of the objects and between two objects having masses. It is the frictional force which acts perpendicular to the surfaces of the two objects.
2. Lubricant
Lubricant is defined as a substance which is used to eliminate friction or wear and tear. It makes an object run smooth and slippery. They are used between two mutually contacting surfaces. Some of the examples of lubricants are oil, ointments, grease, etc.
3. Normal force
Normal force is a force that can resist moving of one object over or against another. It is a contact force and it exist when there is contact between two objects.