Example: two persons a, b observe lighting pulses, from point of a,x1=6×104m,t1=2×104s;x2=12 ×104m,t2=1×104s, from the point of b,two events happen at the same time (1) find the relative velocity of b to a (2) find the space separation of lighting pulses measured by b Solution △ △tExample:two persons a,b observe lighting pulses, from point of a, x1=6104m ， t1=2 10-4 s ； x2=12 104m， t2=1 10-4 s，from the point of b, two events happen at the same time （1）find the relative velocity of b to a （2）find the space separation of lighting pulses measured by b       − −  = x c v t t 2 2 1 1  2 2 1 −   −    = x c v t t Solution: