Advertisements
Advertisements
प्रश्न
A RADAR sends a signal with a speed of 3 x 108 m s-1 to an aeroplane at a distance of 300 km from it. After how much time is the signal received back after reflection from the aeroplane?
उत्तर
Given, d = 300 km
Converting km to m, we get,
1 km = 1000 m
Therefore, 300 km = 3,00,000 m
Hence, d = 3 × 105 m
Speed of sound transmitted from RADAR (V) = 3 × 108 m/s
Since the signal travels twice, that is, when transmitted and when it is being received by the RADAR, the distance is calculated twice i.e. 2d
As we know,
Speed of Sound (V) = `"Total distance travelled (2d)"/("Time interval " ("t")`
∴ `3 xx 10^8 = (2 xx (3 xx 10^5))/("t")`
∴ t = `(2 xx (3 xx 10^5))/(3 xx 10^8)`
∴ t = `2/10^3`
∴ t = 2 × 10-3 s
APPEARS IN
संबंधित प्रश्न
A pendulum has a frequency of 5 vibrations per second. An observer starts the pendulum and fires a gun simultaneously. He hears echo from the cliff after 8 vibrations of the pendulum. If the velocity of sound in air is 340 ms-1, find the distance between the cliff and the observer.
Figure below shows the distance-displacement graph of two waves A and B. Compare
- the amplitude,
- the wavelength of the two waves.
A sound made on the surface of a lake takes 3 s to reach a boatman. How much time will it take to reach a diver inside the water at the same depth?
Velocity of sound in air = 330 ms−1
Velocity of sound in water = 1450 ms−1
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.
An observer standing in front of a vertical wall claps 10 times one second. He adjusts his distance from the wall in such a way that the second of his clapping coincides with the echo. This happens when bis distance from the wall is 17.5m. What is the velocity of sound heard by him?
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 instrument is able to detect the reflected waves from an enemy aeroplane, after a time interval of 0.02 milliseconds. If the velocity of the waves is 3 × 108 ms−1, calculate the distance of the plane from the radar.
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]
A man standing in front of a vertical cliff fires a gun. He hears an echo after 35s. On moving close to the cliff by 82.5 m he fires again. This time he hears the echo after 2.55s. Calculate the speed of sound, distance, and the initial position of man from the cliff.
