Sound travels at a speed of about 344 m/s in air. You see a distant flash of lighting and hear the thunder arrive 7.6 seconds later. How many miles away was the lighting strike? (assume the light takes essentially no time to reach you.)

Express your answer to two significant figures and include the appropriate units.

0.056 miles away

Explanation:

From sound wave,

v = 2x/t ... Equation 1

Where v = velocity of sound in air, x = distance of echo, t = time.

making x the subject of the equation,

x = 2v/t ... Equation 2.

Given: v = 344 m/s, t = 7.6 s.

Substituting into equation 2

x = 2 (344) / 7.6

x = 90.53 m.

x = 90.53/1609.344

x = 0.056 mile.

Thus the lighting strike 0.056 miles away