Question

How does lubricating a machine affect the output force exerted by the machine?

Answer 1

it reduces the friction, thus the net force we need to apply becomes less.

Explanation:

You may know that no surface is 100% plain (or smooth). there are depressions and pores on every surface (even when they look very much plain)

These depressions can lead us to wear and tear the two surfaces rubbed in contact with each other. And this is what, what happens in a machinery.

So to pour these depressions we use oil or paint etc as lubricants to reduce friction caused by rubbing of machenical parts.

{this also explains why you get slipped when you step on the water is lying on the floor.}