| 1. | Mass flow occurs as a result of external forces .
质体流动的发生是由于外力的结果。 |
| 2. | An external force is one whose source is outside the system .
外力是来源于系统之外的力。 |
| 3. | At equilibrium the resultant of all external forces vanish .
在平衡时，所有外力的合力为零。 |
| 4. | The external forces include reactions (r)as well as applied loads(p) .
外力包括反力R和施加力荷载P。 |
| 5. | The velocity of the center of mass is constant in the absence of external forces .
在无外力时，质心的速度是常量。 |
| 6. | The easiest way to rid a system of external torque is to rid it of all external forces .
要去掉系统的外转矩，最简易的办法是去掉一切外力。 |
| 7. | When several external forces act on a body, we may wish to consider the works of the separate forces .
当几个外力作用于一个物体时，我们可能希望考查各个力所作的功。 |
| 8. | This effect is due to the high radial compression produced by the external forces acting at the supports .
此种效应是由于作用在支点的外力所产生的高度径向压缩而引起的。 |
| 9. | When a body is at rest, or in motion with constant velocity, the external force acting upon it are in equilibrium .
当物体处于静止或作匀速运动时，作用在其上的外力是平衡的。 |
