物体的加速度与所受的合外力成正比,与物体的质量成反比。加速度的方向与合力的方向相同。
The alternation of motion is ever proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed.
没有实用性的创新只是噪音,农民需要真正的解决方案。