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在普物力学中,当确定了坐标系,对质点的位置能给予准确的描述之后,描述质点运动状态的物理量有速度、动能、动量、角动量等四个。它们都是为了定量表述质点运动的规律与特征而引用的。当我们用质点运动的一般规律去处理具体的质点运动时,只有首先把握这些描述其运动状态的物理量,才能得到质点运动的具体规律。 在运动学中,对应质点的运动学规律,我们以速度来描述质点的运动状态。它以空间对时间的变化率反映了质点运动的快慢与空间指向。如果知道了速度随时间变化的函数关系,则可求得质点空间位置随时间变化的规律。例如已知质点沿X轴作直线运动的速度为V=dx/d=V-o+at,则从
In general mechanics, when the coordinate system is defined and the position of the particle can be given an accurate description, the physical quantities describing the particle motion state include the velocity, kinetic energy, momentum and angular momentum. They are all quoted in order to quantitatively express the laws and features of particle motions. When we use the general law of particle movement to deal with a specific particle movement, we can get the concrete law of particle movement only by first grasping these physical quantities describing their movement states. In kinematics, corresponding to the kinematic laws of particles, we describe the state of motion of particles with speed. It reflects the rate of change of space on the speed of mass movement and spatial orientation. If we know the function of velocity as a function of time, we can get the law that the spatial location of particles changes with time. For example, it is known that the velocity of the particle moving along the X axis in a straight line is V = dx / d = V-o + at,