Tag: physics

Questions Related to physics

The phenomenon of sound propagation in air is 

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

  1. Isothermal process

  2. Isobaric process

  3. Adiabatic process

  4. None of these

Show answer
Correct Option: C
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.

Mark correct option(s): 

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

  1. In gas sound wave is always longtudinal wave

  2. In liquid, sound wave is always transverse wave

  3. In solid, sound waves may be transverse wave motion

  4. In solid sound wave may be longitudinal wave motion

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Correct Option: D

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

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

  1. west-east

  2. south-north

  3. Up-down

  4. None of these

Show answer
Correct Option: B
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.

Sound travels in air if

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

  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.

Show answer
Correct Option: C
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.

An observer heard his echo $2.5$ seconds after he produced the sound by standing before a wall $400$ m away from him. The speed of sound in air is ____ m/s

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

  1. $320$

  2. $160$

  3. $330$

  4. $200$

Show answer
Correct Option: D

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 :

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

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

Show answer
Correct Option: B
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.$v=\dfrac { 2d }{ t _1-t _2 } m/s$.

A man stands at a distance of $250m$ from a cliff. He  fires a gun and heard the echo after $1.5$ second . What will be the velocity of the second?

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

  1. $333.3m/s$

  2. $330m/s$

  3. $320m/s$

  4. $33.3m/s$

Show answer
Correct Option: C

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?

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

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

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

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

  4. ${ 335 ms }^{ -1 }$

Show answer
Correct Option: A
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 $v=d/t=450/1.5=300 m/s$

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

Given that speed of sound= 342m/s

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

  1. 5100 m

  2. 22.66m

  3. 5130 m

  4. 22.8 m

Show answer
Correct Option: C
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 $= 342 \times 15 = 5130 m$

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 $66m$.

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

  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.

Show answer
Correct Option: A