Advertisements
Advertisements
Question
A radar sends a signal to an aircraft at a distance of 30 km away and receives it back after 2 x 10-4 seconds. What is the speed of the signal?
Solution
Given t =2 x10-4
d = 30 km = 30 x 103 m
Speed of the signal = ?
Let ‘d’ be the distance of aircraft from the radar, then the total distance travelled by the wave in coming and going back = 2 d.
`"Velocity of wave, V"=("Total distance travelled, 2d")/"Time taken, t"`
`=(2xx30xx10^3)/(2xx10^-4)`
`=3xx10^8 `m/s
RELATED QUESTIONS
What should be the minimum distance between source and reflector in water so that echo is heard distinctly?
(The speed of sound in water = 1400 m 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 wave in sea water is 1400 m s-1, find the depth of the sea.
A person standing at a distance x in front of a cliff fires a gun. Another person B standing behind the person A at a distance y from the cliff hears two sounds of the fired shots after 2s and 3s respectively. Calculate x and y (take speed of sound 320 m/s-1).
Figure below shows the distance-displacement graph of two waves A and B. Compare
- the amplitude,
- the wavelength of the two waves.
A boy standing in front of a wall at a distance 17 m produces 10 claps per second. He notices that the sound of his clapping coincides with the echo. Echo is heard only once when clapping is stopped. Calculate the speed of sound.
A person fires a gun while standing at a distance of 850 m from a building. If the speed of sound is 350 ms, calculate the time in which the person hears an echo of the gun flte.
A boy stands 66.4 m in front of a high wall and then blows a whistle. Calculate the time interval when he hears an echo. (Speed of sound = 332m/s).
A ship which is stationary at a distance of 680 m from the shore, sends a signal to the coast. Its echo is heard in 4s. Find the velocity of sound.
An observer stands at a certain distance away from a cliff and produces a loud sound. He hears the echo of the sound after 1.8 s. Calculate the distance between the cliff and the observer if the velocity of sound in air is 340 m−1.
A man stands in between two parallel cliffs and blows a whistle. He hears first echo after 0.6s and second echo after 2.4s. Calculate the distance between cliffs.
[Speed of sound = 336 m/s]
