Echo

Q. The technique used by bats for navigation and location of food is:

1. Echolocation
2. Reflection of light
3. Echocardiography
4. Ultrasonography

Q.

Ram is standing $165m$ behind Shyam. Shyam is standing '$d$' meters away from a wall in the same line. Ram claps and Shyam hears the clap two times at an interval of $2$ seconds. Find the value of '$d$'. (Assume velocity of sound to be $330m{s}^{-1}$)

1. $165m$
2. $660m$
3. $82.5m$
4. $330m$

Q. A boy stands between the two walls as shown below and he claps his hands.


If ‘x’ is less than $60m$ and the time between the first and the second echo is $0.25s$, then calculate the distance ‘x’.
Velocity of sound in air is $344m{s}^{-1}$.

1. $36m$
2. $34m$
3. $17m$
4. $40m$

Q.

Why echoes can't be heard in a small room?

1. Because time gap between direct sound and reflected sound is too low to be perceptible by human ear

2. Because small rooms reflect less amount of energy

3. Because small rooms absorb more sound

4. Because of multiple reflections in small rooms

Q.

The speed of sound in air is 344 m/s. In order to hear distinct echoes in air, the distance of the obstacle from the source of sound should be:

1. at most 17.2 m

2. at least 17.2 m

3. equal to 17.2 m

4. depends on the medium

Q. If a child hears an echo from a cliff 6 second after the sound produced by shouting, how far is the cliff?

1. 58 m
2. 1032 m
3. 68 m
4. 1000 m

Q. To hear an echo, time interval between the original sound and the echo is ___.

1. 0.05 s
2. less than 0.1 s
3. less than 0.05 s
4. more than 0.1 s

Q.

Statement 1: Ram is standing at a distance of 33 m from a wall. He claps and hears the echo of his own clap.
Statement 2: Velocity of sound in air is 330 m/s and time of persistence for hearing is $\frac{1}{10}$ of a second.

1. Statement 1 is false but information in statement 2 is insufficient to prove it

2. Statement 1 is false and information in statement 2 is sufficient to prove it

3. Statement 1 is true and information in statement 2 is sufficient to prove it

4. Statement 1 is true but information in statement 2 is insufficient to prove it

Q.

A man standing in front of a vertical cliff fires a gun and hears the echo after $4$ seconds. He moves $150m$ towards the cliff and again fires the gun. This time, he hears the echo after $3.6$ seconds. Find the distance of the cliff from his first position.

1. $7500m$

2. $550m$

3. $750m$

4. $1500m$

Q.

What is an echo?

1. Reflection of sound reaching to the listener some time before direct sound

2. Reflection of sound reaching to the listener some time after direct sound

3. Reflection of sound reaching to the listener with direct sound

4. Depends on position of listener