Embibe Experts Solutions for Chapter: Waves, Exercise 1: BITSAT 2017

Two sources of sound $A$ and $B$ are moving towards and away from a stationary observer with the same speed respectively. If the frequency of the sound produced by both the sources is equal to $400 \mathrm{Hz}$, then the speed of sources (approximately) if the observer detects 4 beats per second, is [Given, speed of sound $=340 \mathrm{m} {\mathrm{s}}^{-1}$]

If sound travels in air with the speed of $340 \mathrm{m} {\mathrm{s}}^{-1}$, then the number of tones present in an open organ pipe of length $2 \mathrm{m}$ for a maximum frequency of $1200 \mathrm{Hz}$, are

A train moves towards a stationary observer with speed $34 \mathrm{m} {\mathrm{s}}^{-1}$. The train blows whistle and its frequency is registered by the observer as ${\nu }_1$. If the train's speed is reduced to $17 \mathrm{m} {\mathrm{s}}^{-1},$ then the frequency registered is ${\nu }_2$. If the speed of sound is $340 \mathrm{m} {\mathrm{s}}^{-1}$, then the ratio $\frac{{\nu }_1}{{\nu }_2}$ is

A whistle of frequency $500\mathrm{Hz}$ tied to the end of a string of length $1.2 \mathrm{m}$ revolves at $400 \mathrm{rev} {\min }^{-1}$. A listener standing some distance away in the plane of rotation of whistle hears frequencies in the range in Hertz. (Speed of sound $=340 \mathrm{m} {\mathrm{s}}^{-1}$)

A transverse wave propagating on a stretched string of linear density $3\times {10}^{-4} {\mathrm{kgm}}^{-1}$ is represented by the equation

$y=0.2\sin (1.5x+60t)$

where, $x$ in metres and $t$ is in seconds. The tension in the string (in Newton) is