The kinetic energy theorem ofmass variable system is derived from the kinetic equationofmass variable body.
从变质量物体的动力学方程出发，推导出变质量系统的动能定理。
2
The kinetic energy theorem ofmass variable system is derived from the kinetic equationofmass variable body. The practical value of it is pointed out using an example.
从变质量物体的动力学方程出发，推导出变质量系统的动能定理。指明其实用价值，并举例加以说明。
3
For the end, an equationofmass flux of jet about time deduced by the differential element method was compared to CFD results, and the influence of design parameters was analyzed.