Speed of sound in air at standard temperature and pressure is:

(Given, the mass of 1 mole of air is 29.0×10^–3 kg and $\mathrm{\gamma } =\frac{7}{5}$)

Two sitar strings A and B playing the note ‘Dha’ are slightly out of tune and produce beats of frequency 5 Hz. The tension of the string B is slightly increased and the beat frequency is found to decrease to 3 Hz. What is the original frequency of B if the frequency of A is 427 Hz?

A rocket is moving at a speed of 200 m s^–1 towards a stationary target. While moving, it emits a wave of frequency 1000 Hz. Some of the sound reaching the target gets reflected back to the rocket as an echo. The frequency of the sound as detected by the target and the frequency of the echo as detected by the rocket respectively are:

The given diagram shows the progression of a harmonic wave from time t to t + $∆t$ where the crest of the wave displaces by $∆x$ . Then the speed of the wave will be:

$$\begin{gathered} 1. \frac{∆t}{∆x} \\ 2. \frac{2∆x}{∆t} \\ 3. \frac{∆x}{∆t} \\ 4. \frac{2∆t}{∆x} \end{gathered}$$

A pipe, 30.0 cm long, is open at both ends.

(i) Which harmonic mode of the pipe resonates a 1.1 kHz source?

(ii) Will resonance with the same source be observed if one end of the pipe is closed ?

Take the speed of sound in air as 330 m s^–1.