对于低速运动的问题可以用经典物理的方法来解决

而对于
velocity near the velocity of light, c Use:

Addition/Subtraction of Velocities
the result of adding two velocities u and v(near c)

V=(u+v)/(1+uv/c^2) u,v in opposite directions

V=(u-v)/(1-uv/c^2) u,v in same directions

从书上抄的

^_^ ^_^