Two sources of sound S$_1$ and S$_2$ are moving towards and away from a stationary observer with the same speed respectively. Observer detects 3 beats per second. Find speed of sources (approximately).

Given, $f_1=f_2=500$ Hz, speed of sound in air = 330 m/s

If the speed of sound in air is 330 m/s then, find the number of tones present in an open organ pipe of length 1 m whose frequency is $\le$ 1000 Hz.

A steel rod 100 cm long is damped at into middle. The fundamental frequency of longitudinal vibrations of the rod are given to be 2.53 kHz. What is the speed of sound in sound is steel?

A pipe of length 85 cm is closed from one end. Find the number of possible natural oscillations of air column in the pipe whose frequencies lie below 1250 Hz. The velocity of sound in air is 340 m/s.

Assertion To hear different beats difference of the frequencies of two sources should be less than 10.

Reason More the number of beats more in the confusion.

The driver of a car travelling with speed $30 \mathrm{~ms}^{-1}$ towards a hill sounds a horn of frequency $600 \mathrm{~Hz}$. If the velocity of sound in air is $330 \mathrm{~ms}^{-1}$, the frequency of reflected sound as heard by driver is :