System of particlesEnvironmentSystem许多质点所组成的系统
System of particles 许多质点所组成的系统 System Environment
System of particlesEnvironmentSystem质点系
System of particles 质点系 System Environment
System of particlesEnvironmentThere is a specialposition（位置)in aSystemsystem of particlesthat moves as ifall of thesystem'smasswasconcentrated（集中）at that point
System of particles System Environment There is a special position (位置) in a system of particles that moves as if all of the system’s mass was concentrated (集中) at that point
System of particlesEnvironmentThis position is called theSystemcenterofmass（质心）We often just call it theCOM
System of particles System Environment This position is called the center of mass (质心). We often just call it the COM
Even though thediver's body isrotating(转动)in acomplicated way, hiscenter of mass movesjust like a singleparticle would.Path followed bycenter of mass
Even though the diver’s body is rotating (转动) in a complicated way, his center of mass moves just like a single particle would. Path followed by center of mass