对受约束的两体问题在其自由方向上引入折合质量，并由此导出了受约束两体问题中质点的折合动能，同时也给出了处理受约束两体问题的一种简便方法。
The reduced kinetic energy is discussed using the reduced mass of the constrained two bodies. Then a simple method to solve the constrained two bodies problem is presented.
从另一方面讲，在空间机构中质点的相对运动不受约束。
Spatial mechanisms, on the other hand, include no restrictions on the relative motions of the particles.
从另一方面讲，在空间机构中质点的相对运动不受约束。
Spatial mechanisms, on the other hand, include no restrictions on the relative motions of the particles.
应用推荐