An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

• 一节运动的物体趋向于仍保持原来的速度的大小和方向运动，静止的物体将永远静止，除非有不平衡的外力迫使它改变这种状态为止。