R P Goyal and S P Tripathi Solutions for Chapter: Sound, Exercise 1: EXERCISE-7(A)

A man standing $25 \mathrm{m}$ away from a wall produces a sound and receives the reflected sound. Calculate the time after which he receives the reflected sound if the speed of the sound in air is $350 \mathrm{m} {\mathrm{s}}^{-1}$.

A man standing $25 \mathrm{m}$ away from a wall produces a sound and receives the reflected sound. If the speed of the sound in the air is $350 \mathrm{m} {\mathrm{s}}^{-1}$ will the man be able to hear a distinct echo? Explain the answer.

A RADAR sends a signal to an aeroplane at a distance $45 \mathrm{km}$ away with a speed of $3 \times {10}^8 \mathrm{m} {\mathrm{s}}^{-1}$. After how much time is the signal received back from the aeroplane?

A man standing $48 \mathrm{m}$ away from a wall fires a gun to calculate the time after which an echo is heard. (The speed of sound in air is $320 \mathrm{m} {\mathrm{s}}^{-1}$).

A ship on the surface of water sends a signal and receives it back from a submarine inside water after $4 \mathrm{s}$. Calculate the distance of the submarine from the ship. (The speed of sound in water is $1450 \mathrm{m} {\mathrm{s}}^{-1}$)

A pendulum has a frequency of $5$ vibrations per second. An observer starts the pendulum and fires a gun simultaneously. He hears an echo from the cliff after $8$ vibrations of the pendulum. If the velocity of sound in air is $340 \mathrm{m} {\mathrm{s}}^{-1}$, find the distance between the cliff and the observer.

A person standing between the two vertical cliffs produces a sound. Two successive echoes are heard at $4 \mathrm{s}$ and $6 \mathrm{s}$. Calculate the distance between the cliffs. (speed of sound in air $= 320 \mathrm{m} {\mathrm{s}}^{-1}$)

On sending an ultrasonic wave from a ship towards the bottom of a sea, the time interval between sending the wave and receiving it back is found to be 1.5 s. If the velocity of the wave in seawater is $1400 \mathrm{m} {\mathrm{s}}^{-1}$, find the depth of the sea.