The velocity of sound in air at 120°C is 397 ms-1. What will it be when the pressure is h

JAMB Physics 2023 321 views
Source: JAMB · 2023

The velocity of sound in air at 120°C is 397 ms-1. What will it be when the pressure is halved and its temperature raised to 183°C?

The velocity of sound in air at 120°C is 397 ms-1. What will it be when the pressure is halved and its temperature raised to 183°C?

  1. 442 ms-1
  2. 428 ms-1 ✓
  3. 473 ms-1
  4. 456 ms-1
Explanation

The speed of sound in a gas depends on temperature, not pressure. So halving the pressure changes nothing.

v ∝ √T (in kelvin). T₁ = 393 K and T₂ = 456 K.

v₂ = 397 × √(456/393) = 397 × 1.077 ≈ 428 ms⁻¹.

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