RIGID EQUILIBRIUM AS EXEMPLIFIED BY BIRDS STANDING ON A BRANCH¹⁾

To enhance the students' interest for studying Theoretical Mechanics, two teaching cases of static equilibrium are designed in this paper, as the static analysis for birds standing on a branch. Some knowledge points, such as the parallelogram of force, the transmissibility of force, the three-force balance intersecting principle and the conditions of rigid body equilibrium, are used to analyze the forces on the bird' legs on a branch; and the function of the woodpecker tail when it pecked the worm. It is a very enjoyable and educational experience for the students, and can raise students' interest in learning and improve teaching results.