Question:
A man fires a gun towards a hill and hears its echo after 5 s.He then moves 340 m towards the hill and fires his gun again.This time he hears the echo after 3 s.Calculate the speed of sound.
Sound
Q 1.
What are the factors speed of sound wave depends upon?
Q 2.
What are ultrasonics?
Q 3.
What is a wave number?
Q 4.
How is sound propagated through a material medium ? What is wave motion ?
Q 5.
How are compressions and rarefactions produced near a source of sound ?
Q 6.
What is infrasonic? Give an example.
Q 7.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 8.
Fill in the blanks :
v = ? × ?
Q 9.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 10.
A hospital uses an ultrasonic scanner to locate tumors in a tissue. What is the wavelength of sound in a tissue is which the speed of sound is 1.7 km/s. The operating frequency of the scanner is 4.2 MHz. (1MHz = 10
6 Hz).
Q 11.
What is audible range ?
Q 12.
The sound of distant horses can be heard by applying the ear to the ground whereas it is inaudible if the ear is held a little distance above the ground.Explain.
Q 13.
Fill in the blanks :
Waves transport _________ not matter.
Q 14.
What type of waves can travel in vacuum? Give example(s).
Q 15.
Explain how sound is produced by your school bell ?
Q 16.
What propagates along with the waves ?
Q 17.
Sounds we hear inform us of the state of world around us,especially of that part of it which our other senses,such as touch and sight,cannot reach.Illustrate this with appropriate examples.
Q 18.
What is speed of sound in air?
Q 19.
Three persons, A, B and C are made to hear a sound travelling through different mediums as given below:
| Persons | Medium |
| A | Iron Rod |
| B | Air |
| C | Water |
Who will hear the sound first? Why?
Q 20.
How are the wavelength and frequency of a sound wave related to its speed?
Q 21.
A sound wave travels at a speed of 339 ms
–1. If its wavelength is 1.5 cm, what is the frequency of the wave?
Q 22.
Give an application use of ultrasonics.
Q 23.
What type of wave is represented by density- distance graph?
Q 24.
A person standing between two vertical cliffs and 680 m away from the nearest cliff,shouted.He heard the first echo after 4 s and the second echo 3 s later.Calculate (a) the speed of sound in air and (b) distance between the two cliffs.
Q 26.
Why do we use upholstered seats in theatres and halls ?
Q 27.
Deaf people can be made to dance to music.Explain how ?
Q 28.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 29.
What is reverberation?
Q 30.
Fill in the blanks :
In a __________ wave the particles of the medium oscillate in a direction perpendicular to the direction in which the wave propagates.
Q 31.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 32.
What is Sound? Why it is important for us?
Q 33.
Guess which sound has a higher pitch: guitar or car horn?
Q 34.
sonar emits pulses on the surface of water which are detected after reflection from its bottom at a depth 1531 m.If the time interval between the emission and detection of the pulse is 2 s,find the speed of : sound in water.
Q 35.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 36.
Explain the working and application of a sonar.
Q 37.
How can you show that sound waves are longitudinal waves ?
Q 38.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 39.
Fill in the blanks :
A ________ (pulse/wave) is a disturbance which is sudden and lasts for a short duration of time.
Q 40.
Fill in the blanks :
If the time interval between original sound and reflected sound is more than 1/10 second then original sound and reflected sound can be heard clearly. This reflected sound is known as _______.
Q 41.
What are wavefronts?
Q 42.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 43.
A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of the sound. What is the time interval between successive compressions from the source?
Q 44.
Distinguish between loudness and intensity of sound.
Q 45.
Calculate the wavelength of a sound wave having a frequency 300 Hz and speed 330 m/s.
Q 46.
A sound wave has a frequency of 2
kHz and wavelengtl 35 cm.How long will it take to travel 1.5 km ?
Q 47.
An engine is approaching a hill at constant speed.When it is at a distance of 0.9 km,it blows a whisde,whose echo is heard by the driver after 5 s.If the speed of sound is 340 m/s,calculate the speed of the engine.
Q 48.
A ship sends out ultrasound that returns from the seabed and is detected after 3.42 s.If the speed of the ultrasound through sea water is 1531 m/s,what is the distance of the seabed from the ship ?
Q 49.
What is the audible range of the average human ear ?
Q 50.
The frequency of a source of sound is 100 Hz.How many times does it vibrate in a minute ?
