Advertisements
Advertisements
Question
A girl is sitting in the middle of a park of dimension 12 m × 12 m. On the left side of it, there is a building adjoining the park and on the right side of the park, there is a road adjoining the park. A sound is produced on the road by a cracker. Is it possible for the girl to hear the echo of this sound? Explain your answer.
Advertisements
Solution
If the time gap between the original sound and reflected sound received by the listener is around 0.1 s, only then the echo can be heard.
Speed of sound in air, v=344 ms−1
The time gap between the original sound and the reflected sound received by the girl
= `18/344"S" - 6/344 "S"`
= 0.035s
As 0.035 s < 0.1 s, therefore no echo will be heard by the girl.
APPEARS IN
RELATED QUESTIONS
What is the audible range of the average human ear?
Fill in the blanks with suitable words.
A sound wave consists of places of higher pressure called ................. and places of................pressure called.................
Name the organs of hearing in our body.
What name is given to the sound waves of frequency too high for humans to hear ?
What type of sound waves are produced by a vibrating simple pendulum ?
Choose the infrasonic waves and ultrasonic waves from the following frequencies :
(i) 10,000 Hz
(ii) 30,000 Hz
(iii) 18 Hz
(iv) 50,000 Hz
(v) 10 Hz
What are infrasonic waves ? Name two animals which produce infrasonic waves.
Three different vibrating objects produce three-types of sounds X, Y and Z. Sounds X and Y cannot be heard by a man having normal range of hearing but sound Z can be heard easily. The sound X is used in hospitals to break kidney stones of a patient into fine grains which then get flushed out with urine. The sound Y is similar to that which is produced during an earthquake before the main shock wave is generated.
(a) What type of sounds are (i) X (ii) Y, and (iii) Z ?
(b) Name one device which can produce sound like X.
(c) Name one device in a science laboratory which can produce sound like Y.
(d) Name one device in our homes which can produce sound like Z.
(e) What is the frequency range of sounds like Z ?
One of the following can hear infrasound. This one is :
Which of the above two graphs (a) and (b) (Fig.12.3) representing the human voice is likely to be the male voice? Give a reason for your answer.
