Question

You are standing at x = 8.0km. Lightning bolt 1 at x=0km and lightning bolt 2 at x = 13.0km. Both flashes reach your eye at the same time. Your assistant is standing at x = 2.0km If your assistant didn't see the flashes at the same time, what is the time difference between the two flashes?

answer in us

Answer 1

let $\Delta t$ be the time difference between the two flashes; flash 1 flashes at time = t and flash 2 at time =t+ $\Delta t$

so the extra distance is traveled by flash 1 in   $\Delta t$ time

i.e $\Delta t=\frac{3000}{3*10^{8}}=10 miliseconds$

for assistant time gap = $\frac{9000}{3*10^{8}}+\Delta t=30 +10=40miliseconds$

Answer 2