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Multiple choice physics study of sound determination of speed of sound by echo problems on sound sound needs a medium

The phenomenon of sound propagation in air is 

  1. Isothermal process

  2. Isobaric process

  3. Adiabatic process

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

the point that there is a local change in temperature due to the compression and rarefaction half$-$ cycles of the waveform and that the these changes occur so quickly that no heat can enter or leave the cycle$,$

So$,$ it callesan adiabatic process$.$
Hence,
option $(C)$ is correct answer.

Multiple choice physics study of sound determination of speed of sound by echo problems on sound sound needs a medium

A sound wave travels from south to north, in which direction do the particles of air move?

  1. west-east

  2. south-north

  3. Up-down

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sound waves are longitudinal waves and the particles of the air move in direction of propagation sound. So if the wave will travel in south-north direction,the particles of the air also travels in south-north direction.

Multiple choice physics study of sound determination of speed of sound by echo problems on sound sound needs a medium

Sound travels in air if

  1. particles of medium travel from one place to another

  2. there is no moisture in the atmosphere

  3. disturbance moves

  4. both particles as well as disturbance travel from one place to another.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A wave is a disturbance caused in a medium. In the case of sound, only the disturbances moves causing the surround air molecules to vibrate to and fro. The disturbance is transmitted in the form of compressions and rarefactions.

Multiple choice physics study of sound determination of speed of sound by echo problems on sound sound needs a medium

If d is the distance between the source of sound and reflector $t _1, t _2$ are times at which echoes are heard, the expression for determination of velocity of sound in air by echo method is :

  1. $\displaystyle \frac{2d}{t _2-t _1}$

  2. $\displaystyle \frac{2d}{t _1-t _2}$

  3. $\displaystyle \frac{4d}{t _1-t _2}$

  4. $\displaystyle \frac{2d}{t _1+t _2}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The speed of the sound, distance traveled and the time taken relationship if the sound is a reflected sound, that is echo, it is given as follows.
$Speed\; of \; sound=\dfrac { 2\times Distance\; traveled\; (m) }{ Time\; taken(s) } $.
In the question it is given that distance traveled by the sound from the source to the reflector is d and the time taken to hear the echo are $t _1$ and $t _2$ seconds.
The speed of the sound wave is calculated as follows.$v=\dfrac { 2d }{ t _1-t _2 } m/s$.

Multiple choice physics study of sound determination of speed of sound by echo problems on sound sound needs a medium

A man stands at a distance of $225 m$ from a cliff. He fires a gun and heard the echo after $1.5 sec$. What will be the velocity of the sound?

  1. ${ 300ms }^{ -1 }$

  2. ${ 340ms }^{ -1 }$

  3. ${ 320 ms }^{ -1 }$

  4. ${ 335 ms }^{ -1 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The echo is the sound reflection from a surface. Thus, total distance be covered by sound is $d=2\times 225=450 m$.

Using , $S=vt$, we get $v=d/t=450/1.5=300 m/s$

Multiple choice physics study of sound determination of speed of sound by echo problems on sound sound needs a medium

An echo returns in 30 s. What is the distance of the reflecting surface from the source? 

Given that speed of sound= 342m/s

  1. 5100 m

  2. 22.66m

  3. 5130 m

  4. 22.8 m
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Time taken by the wave to travel from the sound to the reflecting surface $= t = \dfrac{30}{2} = 15 m$
Speed $= 342 m/s$ 
Distance of reflecting surface from the sound $= 342 \times 15 = 5130 m$

Multiple choice physics study of sound determination of speed of sound by echo problems on sound sound needs a medium

A man standing in front of a large wall claps at a regular frequency of $10Hz$. He finds that the echoes coincide with his clapping. (The speed od sound in air is $330ms^{-1}.)$
(i) Time taken between successive clapping is $0.1s$.
(ii) The distance between the man and the wall, after he clapping, If he hears one more echo is $33m$.
(iii) The distance between the man and the wall, after he stops clapping, if he hears four more echoes is $66m$.

  1. Only (i) and (ii) are correct.

  2. Only (ii) and (iii) re correct.

  3. Only (i) and (iii) are correct.

  4. All (i), (ii) and (iii) are correct.
Reveal answer Fill a bubble to check yourself
A Correct answer