Does a soccer ball go faster in the air on a cold or hot day?
On a hot day, the air molecules have much kinetic energy - they move more freely. They will move out of the way of the soccer ball that is moving by them more easily when the air is warm. In physics we might say that the warmer air is more susceptible to shear force than cooler air. The warmer air will "part" more simply to let the ball pass through.