If a train is 100 kilometers away, how much sooner would you hear the train coming by listening to the rails (iron) as opposed to listening for it standing by the track? In other words, how much faster will the sound travel through the iron rails than through the air? Assume the air temperature is 0°C. Sound will reach you seconds sooner.

Question

Jaylee Crane

Physics

14 February, 10:10

If a train is 100 kilometers away, how much sooner would you hear the train coming by listening to the rails (iron) as opposed to listening for it standing by the track? In other words, how much faster will the sound travel through the iron rails than through the air? Assume the air temperature is 0°C. Sound will reach you seconds sooner.

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Answers (1)

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Aubrie Livingston · Answer 1

From tables, the speed of sound at 0°C is approximately

V₁ = 331 m/s (in air)

V₃ = 5130 m/s (in iron)

Distance traveled is

d = 100 km = 10⁵ m

Time required to travel in air is

t₁ = d/V₁ = 10⁵/331 = 302.12 s

Time required to travel in iron is

t₂ = d/V₂ = 10⁵/5130 = 19.49 s

The difference in time is

302.12 - 19.49 = 282.63 s

Answer: 283 s (nearest second)