Question:
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.
Answer:
(i) A buzzing fly informs us the presence of a nuisance.Had it not buzzed,we would have paid it no mind.
(ii) The lawn mower’s putt-putt tells us that our neighbour has finaly got around to cleaning up the jungle in his garden - disappearance of a nuisance.
(iii) The sound of a teakettle informs us that the time has come for a coffee break-presence of refreshment.
Thus,these sounds arouse various emotions -anger at the fly,satisfaction that your neighbour has ultimately got across the hint to clean the forest,and desire for coffee.
Sound
Q 1.
Fill in the blanks :
v = ? × ?
Q 2.
What are the factors speed of sound wave depends upon?
Q 3.
Why do we use upholstered seats in theatres and halls ?
Q 4.
What propagates along with the waves ?
Q 5.
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 6.
Explain how sound is produced by your school bell ?
Q 7.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 8.
What is a wave number?
Q 9.
Explain how the human ear works.
Q 10.
What are ultrasonics?
Q 11.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 12.
Calculate the wavelength of a sound wave having a frequency 300 Hz and speed 330 m/s.
Q 13.
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 14.
What are wavefronts?
Q 15.
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 16.
Fill in the blanks :
Waves transport _________ not matter.
Q 17.
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 18.
How is sound propagated through a material medium ? What is wave motion ?
Q 19.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 20.
A boat anchor is rocked by waves whose consecutive crests are 100 m apart.If the wave speed of the moving crests is 20 m/s,calculate the frequency at which the boat rocks.
Q 21.
Deaf people can be made to dance to music.Explain how ?
Q 22.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 23.
Can sound wave travel in vacuum?
Q 24.
What is infrasonic? Give an example.
Q 25.
A bat emits ultrasonic sound of frequency 100 kHz in air.If this sound meets a water surface,what is the wavelength of (a) the reflected sound wave (b) the transmitted sound wave ?
Given speed of sound in air = 340 m/s and in water = 1486 m/s.
Q 26.
Radio Ceylon broadcasts at 25 m.What is the frequency of the station ?
Q 27.
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 28.
Distinguish between loudness and intensity of sound.
Q 29.
Write the name of the wave which propagates in terms of compressions and rarefactions.
Q 30.
Discuss the role of medium in the propagation of sound.
Q 31.
What travels faster : a rifle bullet or the sound of the shot fired from it ?
Q 32.
Try to imagine what you would feel, what sort of person you would be,had you been born totally deaf.
Q 33.
Fill in the blanks :
If a body repeats its back and forth, to and fro or up and down motion along a certain path, about a fixed point, in a certain time interval then the motion of such objects is said to be _____________.
Q 34.
Fill in the blanks :
Audible sound range is _________ to _____________.
Q 35.
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 36.
A man standing at 51 m from a wall fires a gun.Calculate the time after which an echo is heard.The speed of sound is 340 m/s.
Q 37.
How does the sound produced by a vibrating object in a medium reach your ear ?
Q 38.
What is the audible range of the average human ear ?
Q 39.
What is reverberation ? How can it be reduced ?
Q 40.
What is sound ? Discuss the method of its production.
Q 41.
How are compressions and rarefactions produced near a source of sound ?
Q 42.
What are transverse waves ?
Q 43.
On what factors does the speed of sound in a material depend ?
Q 44.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 45.
Fill in the blanks :
RADAR (Radio Detection And Ranging) works on _____________ principle which is used to determine the velocities and movement of aircrafts.
Q 46.
What type of wave is represented by density- distance graph?
Q 47.
A longitudinal wave is produced on a slinky.The frequency of the wave is 25 Hz and it travels at a speed of 20 cm/s. Find the separation between consecutive positions of maximum compressions.
Q 48.
A sound wave has a frequency of 2
kHz and wavelengtl 35 cm.How long will it take to travel 1.5 km ?
Q 49.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 50.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given medium.
