One thing I do on a daily basis is drop things. For example, pieces of paper or folders. When these things fall, they have the force of mg down, and the force of air resistance up. The paper will reach a terminal velocity and continue to fall at this velocity until it hits the ground. The force that the paper exerts on the floor is equal to the force the floor exerts on the paper. The coefficient of friction between the tile floor and the paper is likely small because the tile is smooth and the paper is also relatively smooth. This means that if the paper was acted on by some force, it would move easily across the floor. When I go to pick up the paper, since the paper's inertia is small, it is easy to pick it up. When I pick up the paper, I increase its potential energy (found by mgh) as I increase its height. When I set it back down on the table, the normal force from the table stops it from going through the table and opposes the force of gravity on the paper.