JEE PHYSICS MCQ: WAVES

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Application +4 | -1

When a train is at a distance of

2 \mathrm{~km}

, its engine sounds a whistle. A man near the railway track hears the whistle directly and by placing his ear against the track of the train. If the two sounds are heard att an interval of

5.2 \mathrm{~s}

, the speed of the sound in iron (material of the rail track) is

(Given that velocity of sound in air is

330 \mathrm{~ms}^{-1}

)

View answer and explanation

Correct option: A

2,325.6 \mathrm{~ms}^{-1}

Option A (

2,325.6 \mathrm{~ms}^{-1}

) is correct because it is the speed of sound in iron calculated using the time difference between hearing the sound through air and the railway track.

More Questions from WAVES

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The source of sound generating a frequency of

3\,\,kHz

reaches an observer with a speed of

0.5

times, the velocity of sound in air. The frequency heard by the observer is A source of sound emits waves with frequency

f\mathrm{ }Hz

V\mathrm{ }m/sec

. Two observers move away from this source in opposite directions each with a speed

0.2\,\,V

relative to the source. The ratio of frequencies heard by the two observers will be Assertion: The wave function of a pulse is given by

y = \frac{3}{{{{\left( {2x + 3t} \right)}^2} + 4}},

it propagates in

(– \mathrm{ve}) \,x

-direction.
Reason: The given wave function is of the form

y = f(kx +\omega t),

which represent a wave travelling in negative

X

-direction. In the fundamental mode, time taken by the wave to reach the closed end of the air filled pipe is

0.01\,\,s

. the fundamental frequency is A rope

5 \mathrm{~m}

long has a total mass of

245 \mathrm{~g}

. It is stretched with a constant tension of

1 \mathrm{~kg}

wt. If it is fixed at one end and shaken by hand at the other end, what frequency of shaking will make it break up into three vibrating segments? Take

g=980 \mathrm{~cm} \mathrm{~s}^{-2}

T

is the reverberation time of an auditorium of volume

V