Umakant Kondapure, Collin Fernandes, Nipun Bhatia, Vikram Bathula and, Ketki Deshpande Solutions for Chapter: Wave Motion, Exercise 4: Evaluation Test

Stationary sound $S$ of frequency $334\mathrm{Hz}$ and a stationary observer $\mathrm{O}$ are placed near a reflecting surface moving away from the source with velocity $2 \mathrm{m} {\mathrm{s}}^{-1} ,$ the apparent frequency of the echo of $S$ considering velocity of sound equal to $334 \mathrm{m} {\mathrm{s}}^{-1}$ is

Two trains $\mathrm{A}$and $\mathrm{B}$ are moving with speeds $20 \mathrm{m} {\mathrm{s}}^{-1}$ and $30 \mathrm{m} {\mathrm{s}}^{-1}$ respectively in the same direction on the same-straight track, with B ahead of A. The engines are at the front ends. The engine of train A blows a whistle.

Assume that the sound of the whistle is composed of components varying in frequency from $f_1=800\mathrm{Hz}$ to $f_2=1120\mathrm{Hz}$ as shown in the figure. The spread in the frequency (highest lowest frequency) is thus $320\mathrm{Hz}$. The speed of sound in still air is $340 \mathrm{m} {\mathrm{s}}^{-1}$

Draw the plot of Intensity heard by $\mathrm{B}$ with frequency ($f$).

Three tuning forks of frequencies $248 \mathrm{Hz}, 250 \mathrm{Hz}, 252 \mathrm{Hz}$ are sounded together. The beat frequency is,

Assertion: Our ears cannot distinguish two notes, one produced by a violin and other by a sitar, if they have exactly the same intensity and same frequency.

Reason: When a musical instrument is played, it produces a fundamental note which is accompanied by number of overtones called harmonics.

A source emitting sound of frequency $f_0$ is moving in a circle of radius $R$, having centre at the origin,-with a uniform speed is $\frac{c}{3}$ where c is the speed of sound. Find the maximum and minimum frequencies heard by stationary listener at the point $(\frac{R}{2},0)$

String-$1$ is connected with string-$2$. The mass per unit length in string- $1$ is ${\mu }_1,$ and mass per unit length in string-$2$ is $4{\mu }_1$. The tension in the strings is T.A travelling wave is coming from the left. What fraction of the energy in the incident wave goes into string-2?

The figure $\left(\mathrm{i}\right)$ shows the graphical representation of the air molecules in a tube of air ($\mathrm{length} = L$) at atmospheric pressure on the absolute pressure $P\left(x\right)$ graph. Which of following pictures corresponds to absolute pressure $P\left(x\right)$ of figure$\left(\mathrm{ii}\right)$?

A sound increases its decibel reading from 20 to 40dB. This means that intensity of sound is