对 t 求导,消去积分符号,v = a ∫(0到t) (1 - v^2/c^2) dt
对两边 t 求导:dv/dt = a (1 - v^2/c^2)
分离变量,两边积分,dv / (1 - v^2/c^2) = a dt
左边:
∫ c dx / (1 - x^2) = c/2 ln |(1+x)/(1-x)|
右边:
∫ a dt = at + C2
代入初始条件,确定常数,初始条件 t = 0, v = v0:
得到c/2 ln |(c+v0)/(c-v0)| = C
代回常数并整理:
(c+v)/(c-v) = e^(2a/c * t) * (c+v0)/(c-v0)
解出 v(t):
v(t) = c * tanh( (a/c) t + tanh^(-1)(v0/c) )