Answer to Question #108897 in Mechanical Engineering for jyothi

Question

you see a sudden flash light,then 6 seconds later you hear the thunder.take the speeds of sound and light as 340ms^-1and3*10^8ms^-1,respectively.how far away was the lightining strike?

Answer 1

According to the equation:

t = d / v

where t - time, d - distanse, v - speed.

As light and sound passed through the same distance and difference between the times required is 6 sec, then:

(d / v_sound) - (d / v_light) = 6

From here:

d (1/vsound - 1/vlight) = 6

d = 6 / (1/v_sound - 1/v_light) = [6 × v_sound × v_light] / [v_light - v_sound]

As v_light >> v_sound, the equation can be written as following:

d = [6 × v_sound × v_light] / v_light = 6 × v_sound = 6 s × 340 m/s = 2040 m = 2.04 km

Answer: 2.04 km