Embibe Experts Solutions for Exercise 6: Assignment Set-2

In a stationary wave pattern that forms as a result of reflection of waves from an obstacle, the ratio of the amplitude at an antinode and a node is $4 : 1.$ Percentage of energy of wave passes across the obstacle is

Two tuning forks with națural frequencies $170 \mathrm{Hz}$ each move relative to a stationary observer. One fork moves away from the observer while the other moves towards him at the same speed. The observer hears beats of frequency $2 \mathrm{Hz}.$ Speed of the tuning fork is $n \mathrm{m} {\mathrm{s}}^{-1}.$ Write the value of $n$ to the nearest ineteger.

(velocity of sound in air is $340 \mathrm{m} {\mathrm{s}}^{-1}$)

A tube $0.75 \mathrm{m}$ long is closed at one end. A stretched wire is placed near the open end. The wire is $0.25 \mathrm{m}$ long and has a mass of $0.01 \mathrm{kg}.$ It is held fixed at both ends and vibrates in its fundamental mode. It sets the air column in the tube into vibration at its fundamental frequency by resonance. If speed of sound is $330 \mathrm{m} {\mathrm{s}}^{-1}$ in air then tension in the wire is $11n \mathrm{N}.$ Value of $n,$ is

Two tuning forks $A$ and $B$ when set in vibration, give $4$ beats per second. If a prong of the fork $A$ is filed, the beats are reduced to $5$ beats per $2$ second. If frequency of fork $B$ is $250 \mathrm{Hz}$ then frequency of $A$ is $3n \mathrm{Hz}.$ Value of $n,$ is

A source is oscillating between $A$ and $C$ with its position varying with time as $y=900 \cos \left(\frac{\pi t}{6}\right),$ where $y$ is in metre. An observer is situated at a distance $12 \mathrm{m}$ along the perpendicular bisector of $AC.$ Frequency emitted by source is $300 \mathrm{Hz}.$ Approximate frequency observed by observer when source is at $O$ is $5n \mathrm{Hz}.$ Value of $n,$ is [Velocity of sound in air $=300 \mathrm{m} {\mathrm{s}}^{-1}$]

First overtone of a closed organ pipe produces beats with first overtone of an open organ pipe with a beat frequency of $2 \mathrm{Hz}.$ Fundamental frequency of closed organ pipe is $55 \mathrm{Hz}.$ If frequency of open organ pipe exceeds that of closed organ pipe, then length of the open organ pipe is $n \mathrm{m}.$ Value of $n,$ is [Speed of sound in air is $330 \mathrm{m} {\mathrm{s}}^{-1}$]

Power of sound from a very small loud speaker is $25 \mathrm{MW}.$ Sound level at a point which is at a distance $r$ from the speaker is $I_1.$ If power of loud speaker is increased to $1000 \mathrm{MW},$ then sound level at a point $2$ raway from the loud speaker is $I_2.$ Value of $I_2-I_1$ is $n \mathrm{dB}.$ Value of $n,$ is

A rod of mass $1.5 \mathrm{kg}$ and length $40 \mathrm{cm}$ is clamped with the help of two identical strings at the two ends as shown. A block of mass $5 \mathrm{kg}$ has to be connected on the rod. What should be the distance (in $\mathrm{cm}$ ) of point of suspension of block from the first end so that same tuning fork can vibrate the first string in second harmonic and the second string in third harmonic? $\left(g=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$