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[2 Mark Questions]

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24 questions · timed · auto-graded

Question 12 Marks
Numerical problem.

A stone is dropped from the top of a tower 750 m high into a pond of water at the base of the tower. Calculate the number of seconds for the splash to be heard? (Given g = 10 m s–2 and speed of sound = 340 m s–1)

Answer
(Given g = 10 m s– 2 and speed of sound = 340 ms– 1)
Height = 750m
h = ut + 0.5 gt2
The initial velocity is 0
750 = 0.5 × 10 × t2
t = 10sec
Speed of sound is $\frac{340 m }{ sec }$
So, time taken to travel 750m upwards is,
$\frac{750}{340}=2.20 s$
time taken = 10 + 2.20 = 12.2 sec.
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Question 22 Marks
Numerical problem.

The frequency of a source of sound is 600 Hz. Calculate the numbner of times it vibrates in a minute?

Answer
The number of vibrations (complete waves or cycles) produced in one second is called frequency of the wave.
Hence, in one minute 600 x 60 vibrations are produced = 36000 (Need clarification)
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Question 32 Marks
What is acoustics?
Answer
Acoustics is a branch of physics that deals with the study of properties of Sound.
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Question 42 Marks
Give two practical applications of reflection of Sound?
Answer
  • SONAR – Reflection of sound is used to measure the distance, direction and speed of underwater objects.
  • Stethoscope – Patient’s heartbeats reach doctor’s ear by multi reflections of sound.
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Question 72 Marks
Which characteristics of the sound helps you to identify your friend by his voice while sitting with others in a dark room?
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Question 182 Marks
A Sound wave travels at a speed of $344 ms ^{-1}$. If the wavelength is $1.5 cm$, what is the frequency of Wave? Will it be audible?
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Question 192 Marks
  • Two persons are at opposite ends of a steel rod. One strikes the end of rod with a stone. Find the ratio of time taken by the sound wave in air and in steel to reach the second person.
    (Sound of speed in steel $=5960 ms ^{-1}$, Sound of speed in air $=344 ms ^{-1}$ )
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Question 202 Marks
An echo returned in $3 s$. What is the distance of reflecting surface from the source given that the speed of sound is $330 ms ^{-1}$.
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Question 212 Marks
A person is listening to a tone of $400 Hz$ from a distance of $500 m$ from the source of sound. What is the time interval between successive compressions from source?
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Question 222 Marks
A body vibrates 3000 times in one minute. If the velocity of sound in air $330 ms ^{-1}$, find (i) Frequency of vibration (ii) Wavelength.
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[2 Mark Questions] - Science STD 9 Questions - Vidyadip