Abstract: This article analyzes in detail the total work done by the microscopic sliding friction forces at the bottom of the small ball in an infinitely small time, and obtains the expression of the elementary displacement of the point of action of the macroscopic sliding friction force. It is pointed out that the action point is a hypothetical concept when the work is done. The actual sliding distance of the small ball is obtained by integration, and the total work done by all sliding friction forces is calculated. It is pointed out that the distance of the small ball sliding plus the distance of the small ball rolling is equal to the displacement of the center of mass of the small ball. It is also pointed out that the sliding and rolling of the small ball are carried out simultaneously rather than alternately. It is proved that, formally, the negative work done by the sliding friction force on the entire displacement of the center of mass of the small ball leads to the decrease of the translational kinetic energy of the small ball, while the positive work done on the reverse rolling distance leads to the of increase in the rotational kinetic energy of the small ball. The main purpose of the article is to reveal the mechanisms of the work done by the sliding friction force acting on a small ball sliding and rolling on the ground.

Key words: small ball rolling while sliding, sliding friction force, work, action point, sliding distance