COMEDK2013PhysicsWaves and Sound
Oxygen is 16 times heavier than hydrogen. Equal volumes of hydrogen and oxygen are mixed. The ratio of speed of sound in the mixture to that in hydrogen is
Options
- A8
- B2 / 17
- C1 / 8
- D32 / 17
Correct answer
B. 2 / 17
Step-by-step solution
Velocity of sound in a gas is given by v= R T M where, = specific heat ratio and M= molecular mass of gas. Fror hydrogen, v_ H = R T M₁ For mixture of gases, molecular mass, Here, M_ mix = n₁ M₁+n₂ M₂ n₁+n₂ n₁=n₂ (for equal volumes) and M₂=16 M₁ (given) M_ mix = M₁+16 M₁ 2 = 17 M₁ 2 Velocity of sound, v_ mix = R T M_ mix Dividing Eq. (ii) by Eq. (i) we get aligned v_ mix v_ H &= R T M_ mix M₁ R T &= M₁ M_ mix = 2 17 aligned