Gene asked in Science & MathematicsPhysics · 6 years ago

# How fast does sound travel?

I was watching fireworks the other day and I realized that the explosion happened seconds before I heard it. I had to have been 3 quarters of a mile away. Is there a ratio for how fast sound travels?

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• 6 years ago

1120 feet per second @ STP

• 6 years ago

For your purpose, the fireworks (and lightning), the rule of thumb is .2 mi per second. So the sound of the crackers should have been reaching you about .6 seconds after you saw the flashes.

If in fact the sound got there "seconds" after the flashes, you were probably more than that 3/4 mi from the works that you thought you were.

• 6 years ago

The speed of sound varies with density.

However yes, the speed of sound is generally given as v = 343 m/s; at 20 degrees Celsius .

• 6 years ago

The speed of sound can change by changing the density of the medium it travels through. Another one is temperature, which can increase the kinetic energy of the sound particles causing it to travel faster.

• 6 years ago

Speed of sound in dry air at 20 degress celsium and atmosphere pressure = 343.2 m/s

20 degrees celsius = 68 degrees fahrenheit

• 6 years ago

speed of sound = sqrt(gamma*R_air*T)

gamma = 1.4 <--- ratio of specific heat

R_air = 287.1 J / (kg K) = 1716.49 ft*lbf / (slug * R) <---- Gas Constant for Air

T = Whatever the temperature is outside... <--- Absolute temp (Kelvin or Rankine)