The rate of change of momentum is proportional to the imposed force and goes in the direction of the force. 物体的加速度跟物体所受的外力成正比,跟物体的质量成反比,加速度的方向跟外力的方向相同。
In particular, the apparent rate of acceleration varies with redshift in a telltale way. 尤其是,这看起来的加速度随着红移的不同显著的变化。