13 - SOUND
Q. 1. Fill in the blanks with the proper words.
(1) The propagation of sound does not occur through a ……………
(2) Noise pollution is a........... issue.
(3) The sound which is disagreeable to the ears is called …………….
(4) Noise has adverse effects on our.............
Ans. (1) The propagation of sound does not occur through a
vacuum.
(2) Noise pollution is a social issue.
(3) The sound which is disagreeable to the ears is called
noise.
(4) Noise has adverse effects on our health / mind / concentration
/ ears
Q. 4. What
should we do?
(1) Silencer of a motorcycle is broken.
Ans. The silencer should be repaired immediately to reduce
noise pollution. Driving such a motorcycle should not be attempted till the
silencer is fixed.
12) A factory in the surroundings is producing continuous
loud noise.
Ans. We should inform about the loud noise to the
authorities of the factories. If there is any problem with machinery in the
factories. It should be repaired by the owners of the factory. If they are not
paying any heed, then we can complain to the nearby police station.
Q. 5. Write the
answers in your words:
(1) What is
meant by vibration?
Ans The rapid oscillations or to and fro movements of an
object is called vibration. Vibrating object have a particular speed.
(2) Explain with the
help of practical examples how sound is propagated through solids.
Ans. Sound propagates with a maximum speed through the solid
medium. We can hear the sound of a train which is far off by placing our ear to
the railway track. If we knock at the door, the person inside the room can hear
it clearly.
(3) What is meant by noise pollution ?
Ans. A condition in which there is continuous unwanted and
unpleasant sound is called noise pollution.
(4) What
measures will you take to control noise pollution?
Ans. (1) Unnecessarily blowing of horns of the vehicles
should be completely prevented,
(2) The entertainment of our homes should not be trouble for
others. Therefore, the volume of TV or radio should be kept at minimum. It
should be restricted only to those who are watching or listening to the
programmes.
(3) Engines of unmaintained vehicles produce lot of unwanted
and harsh sound Therefore, maintenance of vehicles should be done. Such noise
should be avoided completely
(4) Factories, airports, railway stations and bus stands,
etc. can create lot of noise. Therefore, they should not be located in the
residential areas. But they should be away from localities where people stay.
Q. 6. Complete the table :
|
Nature of sound |
Unpleasant |
Pleasant |
|
Speaking |
Speaking in shouting and harsh
tone |
Soft speech |
|
Whispering |
|
Yes |
|
Aeroplane sounds |
Yes |
|
|
Horns of vehicles |
Yes |
|
|
Railway engine |
Yes |
|
|
Rustling of leaves |
|
Yes |
|
Neighing of a horse |
|
Yes |
|
Ticking of a clock |
|
Yes |
