HARD

9th CBSE

IMPORTANT

Earn 100

A man standing between two parallel cliffs fires a gun. He hears the first echo after $1.5 s$ and the next after $2.5 s$ . Calculate the distance between the cliffs. When does he hear the third echo? Take the speed of sound in air is $340 m s^{- 1}$ .

Important Questions on Sound

HARD

9th CBSE

IMPORTANT

Physics For Class 9>Chapter 5 - Sound>Exercise>Q 7

A person standing between two vertical cliffs and

680 m

away from the nearest cliff, shouts. He heard the first echo after

4 s

and the second echo

3 s

later. Determine (ï) the speed of sound in air and (ii) distance between the two cliffs.

HARD

9th CBSE

IMPORTANT

Physics For Class 9>Chapter 5 - Sound>Exercise>Q 8

A girl stands

60 m

in front of a wall and claps. She continues to clap every time an echo is heard. Another girl watches her and observes that the time between the first (

1 st

) and the fifty first (

51 st

) clap is

18 s

. What is the speed of sound?

HARD

9th CBSE

IMPORTANT

Physics For Class 9>Chapter 5 - Sound>Exercise>Q 9

A man fires a shot and hears an echo from a cliff after

2 s

. He walks

85 m

towards the cliff and the echo of a second shot is now heard after

1.4 s

. Calculate the velocity of sound and find how far was the man from the cliff when he first heard the echo?

MEDIUM

9th CBSE

IMPORTANT

Physics For Class 9>Chapter 5 - Sound>Exercise>Q 10

An engine is approaching a hill at constant speed. When it is at a distance of

0.9 km

, it blows a whistle, whose echo is heard by the driver after

5 s

. If the speed of sound is

340 m s^{- 1}

, find the speed of the engine.

MEDIUM

9th CBSE

IMPORTANT

Physics For Class 9>Chapter 5 - Sound>Exercise>Q 11

It takes

2.4 s

to record the echo of a sonar. If the speed of sound in water is

1450 m s^{- 1}

, calculate the depth of the ocean floor.

MEDIUM

9th CBSE

IMPORTANT

Physics For Class 9>Chapter 5 - Sound>Exercise>Q 12

A ship sends out ultrasound that returns from the seabed and is detected after

3.42 s

. If the speed of the ultrasound through seawater is

1531 m s^{- 1}

. Calculate the distance of the seabed from the ship.

MEDIUM

9th CBSE

IMPORTANT

Physics For Class 9>Chapter 5 - Sound>Exercise>Q 13

A ship which is stationary, is at a distance of

2900 m

from the seabed. The ship sends an ultrasound signal to the sea bed and its echo is heard

4 s

. What is the speed of sound in water?

MEDIUM

9th CBSE

IMPORTANT

Physics For Class 9>Chapter 5 - Sound>Exercise>Q 1

Consider the following sound waves marked

A

B

C

and

D

:
(a) Which two waves represent sounds of the same loudness but different pitch?
(b) Which two waves represent sounds of the same frequency but different loudness?
(c) State whether all these sound waves have been produced by the same vibrating body or different vibrating bodies?
(d) Which vibrating body/bodies could have generated the sound waves shown here?
Question Image

A man standing between two parallel cliffs fires a gun. He hears the first echo after 1.5 s and the next after 2.5 s. Calculate the distance between the cliffs. When does he hear the third echo? Take the speed of sound in air is 340 m s-1.

Important Questions on Sound

Learn and Prepare for any exam you want !

A man standing between two parallel cliffs fires a gun. He hears the first echo after $1.5 s$ and the next after $2.5 s$ . Calculate the distance between the cliffs. When does he hear the third echo? Take the speed of sound in air is $340 m s^{- 1}$ .