EASY

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Will the velocity of sound depend upon the molecular mass of the gas?

Important Questions on Sound Waves

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A bomb explodes at time

t = 0

in a uniform, isotropic medium of density

ρ

and releases energy

E

, generating a spherical blast wave. The radius

R

of this blast wave varies with time

t

EASY

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Two waves of sound of wavelength

1.2 m

and

1.25 m

in a medium produce

90

beats in

10 s .

The speed of sound in the medium is

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Consider a gas with molar mass

M .

If the sound at frequency

f

is introduced to a tube of this gas at temperature

T

then an internal acoustic standing wave is set up with nodes separated by

L .

The adiabatic constant

(γ = \frac{C_{p}}{C_{v}})

EASY

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

The velocity of sound in air is independent of change in

EASY

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Sound waves of wavelength

λ

and velocity

v

in medium-

1

enter medium-

2

. If their velocity in medium-

2

4 v

, the wavelength in medium-

2

HARD

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Sound travels in a mixture of two moles of helium and

n

moles of hydrogen. If rms speed of gas molecules in the mixture is

\sqrt{2}

times the speed of sound, then the value of

n

will be

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A sound wave of frequency

200 Hz

is travelling in air. The speed of sound in the air is

340 m s^{- 1} .

What is the phase difference at a given instant between two points separated by a distance of

85 cm

along the direction of propagation?

EASY

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Sound travels fastest in

EASY

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

It takes

2.0

seconds for a sound wave to travel between two fixed points when the day temperature is

10 ° C

. If the temperature rises to

30 ° C

, the sound wave travels between the same fixed parts in

EASY

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A hospital uses an ultrasonic scanner to locate tumors in a tissue. The operating frequency of the scanner is

4.2 MHz .

The speed of sound in a tissue is

1.7 km / s .

The wavelength of sound in the tissue is

EASY

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

When sound travels from air to water the quantity that remains unchanged is

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A tunning fork of frequency

480 H z

is used in an experiment for measuring speed of sound

(v)

in air by resonance tube method. Resonance is observed to occur at two successive lengths of the air column,

l_{1} = 30 c m

and

l_{2} = 70 c m .

Then,

ν

is equal to:

HARD

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A person in front of a mountain is beating a drum at the rate of

40

per minute and hears no distinct echo. If the person moves

90 m

closer to the mountain, he has to beat the drum at

60

per minute to not hear any distinct echo. The speed of sound is

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Let the speed of sound at

0 ° C

332 {m s}^{- 1}

. On a winter day sound travels

342 m

in one second. The atmospheric temperature on that day is

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

The pressure wave,

P = 0.01 \sin [1000 t - 3 x] N m^{- 2}

, corresponds to the sound produced by a vibrating blade on a day when atmospheric temperature is

0 ° C

. On some other day when temperature is

T

, the speed of sound produced by the same blade and at the same frequency is found to be

336 m s^{- 1}

. Approximate value of

T

is:

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Consider a system of gas of a diatomic molecule in which the speed of sound at

0^{o} C

1260 m s^{- 1}

. Then, the molecular weight of the gas is in

g {mol}^{- 1}

, (given, the gas constant

R

8 .314 J {mol}^{- 1} K^{- 1}

)

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

STATEMENT - 1: If an observer places his ear at the end of a long steel pipe, he can hear two distinct sounds, when a workman hammers the other end of the pipe. Because

STATEMENT - 2: Longitudinal as well as transverses wave can be propagated in steel.

EASY

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

The Newton's formula for the velocity of the longitudinal waves in a medium is expressed as

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

The speed of sound in oxygen ( O₂ ) at a certain temperature is 460 ms^-1 . The speed of sound in helium ( He ) at the same temperature will be ( assume both gases to be ideal )

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A source of sound of frequency 600 Hz is placed inside water. The speed of sound in water is

1500 m s^{- 1}

and in air it is

300 m s^{- 1}

. The frequency of sound recorded by an observer who is standing in air is

Will the velocity of sound depend upon the molecular mass of the gas?

Important Questions on Sound Waves

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