third law of motion

例句：

1. 1. The thirdlaw of motion states that the total energyof a system is conserved.
   第三定律指出系统的总能量是守恒的。
2. 2. Thethird law of thermodynamics explains whyheat cannot be created or destroyed.
   热力学第三定律解释了为什么热量不能被创造或销毁。
3. 3. In the third law of thermodynamics, work done by an externalforce is equal to the change in internalenergy.
   在热力学第三定律中，外部力所做的功等于内部能的变化。