## Question

(a) Speed of sound in air is 332 m/s at NTP. What will be the speed of sound in hydrogen at NTP if the density of hydrogen at NTP is (1/16) that of air? [Assume ρ_{air}/ρ_{H} â‰ƒ 1.]

(b) Calculate the ratio of the speed of sound in neon to that in water vapours at any temperature. [Molecular weight of neon = 2.02 × 10^{–2}kg/mol and for water vapours = 1.8 × 10^{–2} kg/mol]

### Solution

1328 m/s & 1.055

The velocity of sound in air is given by

(a) In terms of density and pressure,

(b) In terms of temperature and molecular weight,

Now as neon is monatomic (γ = 5/3) while water vapours polyatomic (γ = 4/3); so

#### SIMILAR QUESTIONS

A travelling wave pulse is given by

In which direction and with what velocity is the pulse propagating? What is the amplitude of pulse?

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Where *x* and *y* are in *m*. The shape of the wave disturbance does not change during the propagation. What is the velocity of the wave?

A wire of uniform cross-section is stretched between two points 1 *m*apart. The wire is fixed at one end and a weight of 9 kg is hung over a pulley at the other end produces fundamental frequency of 750 Hz. (a) What is the velocity of transverse waves propagating in the wire? (b) If now the suspended weight is submerged in a liquid of density (5/9) that of the weight, what will be the velocity and frequency of the waves propagating along the wire?

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