Abstract: With the help of the friction between tennis balls, the tennis balls can be formed into a multi-layer “tennis-ball tower”. The problem of “tennis-ball tower” is interesting, scientific and comprehensive, and the study of this problem is of great significance to exercise the comprehensive physical literacy of college students. In this paper, firstly, the selected tennis balls can be regarded as rigid bodies, which is proved by experiments on deformation degree and contact area. Secondly, the relationship between the static friction coefficient and the supporting force on the balls is measured considering factors like the stripes on the balls and so on, and the theoretical mechanics analysis and the solution method of the stable tennis-ball tower are given. They are proved by the Adams simulation and practical experiments. Finally, it is pointed out that when the number of balls is the same in all layers except the top layer, the structure of the tennis-ball tower can be changed by changing the stacking density of the balls or constructing the “coupling” structure, and the statically indeterminate problem in the correlated solution is discussed. 

Key words: tennis-ball tower, rigid body, coefficient of friction