Factors Affecting the Speed of Sound in Air

Factors Affecting the Speed of Sound in Air MDCAT MCQs with answers

11 past paper MCQs on Factors Affecting the Speed of Sound in Air, from the Waves unit of MDCAT Physics. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

Read the notes first Practise the unit as a quiz

1.The speed of sound in an ideal gas depends upon its: (MDCAT 2023)

  1. temperature
  2. frequency
  3. amplitude
  4. wavelength
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Correct answer: (a) temperature

$v\propto\sqrt{T}$; the frequency, amplitude and wavelength of the sound do not change it.

2.Speed of sound in air increases with: (KMU MDCAT 2025)

  1. Higher temperature, higher humidity
  2. Lower temperature, lower humidity
  3. Higher pressure at constant temperature
  4. Higher density at constant elasticity
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Correct answer: (a) Higher temperature, higher humidity

Sound travels faster in warmer air, and water vapour is lighter than the air it displaces, so humidity helps too.

3.If the speed of sound is measured at sea level and at the top of a mountain, both at the same temperature, it will be: (SZABMU MDCAT 2025)

  1. Greater at sea level
  2. Greater at the mountain top
  3. The same at both places
  4. Greater where the air is denser
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Correct answer: (c) The same at both places

The speed of sound depends on the temperature of the air, not on its pressure or density.

4.Which of the following factor does not affect the speed of sound in air? (SZABMU MDCAT 2023)

  1. Pressure
  2. Density
  3. Temperature
  4. Medium
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Correct answer: (a) Pressure

Raising the pressure raises the density in the same proportion, so $\sqrt{P/\rho}$ is unchanged.

5.The increase in the speed of sound for each degree rise above 0o C is: (SZABMU MDCAT 2023)

  1. 0.61 m/s
  2. 0.51 m/s
  3. 0.41 m/s
  4. 0.31 m/s
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Correct answer: (a) 0.61 m/s

Sound gains about $0.61\,\mathrm{m\,s^{-1}}$ for each degree above $0^{\circ}\mathrm{C}$.

6.With increase in pressure, the speed of sound will: (NUMS MDCAT 2023)

  1. Increase
  2. Decrease
  3. First increase then decrease
  4. Remain the same
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Correct answer: (d) Remain the same

Raising the pressure raises the density in the same proportion, so the speed is unchanged.

7.Speed of sound does not depend on: (PMC MDCAT 2022)

  1. Pressure
  2. Density
  3. Adiabatic Index
  4. Amplitude
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Correct answer: (a) Pressure

Raising the pressure raises the density in the same proportion, so $\sqrt{\gamma P/\rho}$ is unchanged.

8.The speed of sound cannot be greater than: (PMC MDCAT 2022)

  1. Speed of shock wave
  2. Speed of light
  3. Speed of water wave
  4. Speed of sound in vacuum
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Correct answer: (b) Speed of light

Nothing carries a signal faster than light, and sound is far slower than that.

9.The increase in the speed of sound in air for each degree rise above 0°C is: (NUMS MDCAT 2022)

  1. 0.40 m/s
  2. 0.51 m/s
  3. 0.81 m/s
  4. 0.61 m/s
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Correct answer: (d) 0.61 m/s

Sound gains about $0.61\,\mathrm{m\,s^{-1}}$ for each degree above $0^{\circ}\mathrm{C}$.

10.The speed of sound in air does not depend on: (NUMS MDCAT 2022)

  1. Density of medium
  2. Pressure
  3. Temperature
  4. Moisture
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Correct answer: (b) Pressure

Raising the pressure raises the density in the same proportion, so the speed is unchanged.

11.The speed of sound in air is 332 m/s. The speed of sound at 22 degrees centigrade will be: (PMC MDCAT 2020)

  1. 345.2 m/s
  2. 340 m/s
  3. 350 m/s
  4. 330 m/s
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Correct answer: (a) 345.2 m/s

$332+0.61\times22$ gives about $345\,\mathrm{m\,s^{-1}}$.

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