If a body is kept free of the action of forces, it will remain in its state of rest or of uniform motion in a straight line.
物体如果不受外力的作用，将保持静止的状态或沿直线作匀速运动。
Every body continues in its state of rest, or in uniform motion in a straight line unless it is compelled to change that state by forces impressed upon it.
物体都保持静止的或沿一条直线作匀速运动的状态，速运动的状态，除非作用在它上面的力迫使它改变这种状态。使它改变这种状态。
This article expounds again whether the mechanical energy is in the uniform motion in a straight line, as the mechanical energy is conservative when the system is in the frame of earth reference.
本文针对系统相对于地球参照系机械能守恒时，在相对于地面作匀速直线运动的参照系中机械能是否依然守恒的问题进行了重新论证。
A body at rest remains at rest, and a body in motion moves with uniform speed in a straight line, unless a force ACTS on it.
如无外力作用，静止的物体始终静止，运动的物体一直作匀速直线运动。
A body at rest remains at rest, and a body in motion moves with uniform speed in a straight line, unless a force ACTS on it.
如无外力作用，静止的物体始终静止，运动的物体一直作匀速直线运动。
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