The speed of sound in air is ~331 m/s. During the next thunderstorm, try to estimate your distance from a lightning bolt by measuring the time lag between the flash and the thunderclap. You can ignore the time for the light flash to reach you. Why?

Question

Freddy Hunt

Physics

4 September, 18:13

The speed of sound in air is ~331 m/s. During the next thunderstorm, try to estimate your distance from a lightning bolt by measuring the time lag between the flash and the thunderclap. You can ignore the time for the light flash to reach you. Why?

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Answers (1)

Know the Answer?

Grant Morrow · Answer 1

Light is significantly faster than sound so we will not be able to recognize the difference between the light of the lightning bolt falling and the light actually reaching our eyes. So, we can ignore the time for the light flash to reach you.

Explanation:

The speed of sound in air is 331 m/s. This means that in 1 second sound covers a distance of 331 m. Lightning causes thunder. In order to know the distance of the lightning bolt we must measure the time thunder takes to reach our ears. After looking at the lightning bolt we must note down the time before we can hear the thunder. Then we multiply the speed of sound in air with the time and we will obtain the distance.

For example we hear thunder after 10 seconds of the bolt falling. Then we multiply the time with the speed and we get the distance i. e., 331*10=3310 m = 3.31 km.

Light is significantly faster than sound so we will not be able to recognize the difference between the light of the lightning bolt falling and the light actually reaching our eyes. So, we can ignore the time for the light flash to reach you.