A body in equilibrium (平衡) must be either at rest (静止) or in motion with constant velocity.
                    举一反三
- Which of the following motions will cause flexible impulse in a cam mechanism? A: Constant velocity motion B: Constant acceleration motion C: Harmonic motion D: Cycloidal motion
 - A body velocity is not constant is said to be accelerated.
 - According to quantity equation the price level would change less the proportionately with a rise in the money supply if there were also A: either a rise in output or a rise in velocity. B: either a rise in output or a fall in velocity. C: either a fall in output or a rise in velocity. D: either a fall in output or a fall in velocity.
 - A body in motion remains in motion at a constant speed in a straight line unless acted upon by an external force. 运用分句法的译文为 .
 - The first condition for equilibrium(平衡) ensures that a body(物体) should be in translational(平动的) equilibrium; the second, that it be in rotational(转动的) equilibrium.
 
