Question

A car approaches a hill with a constant speed. When it is at a distance of 0.96 km, it blows horn whose Eco is heard by the driver 3 second later. If the speed of the sound in air is 300 m/s. Then calculate the speed of the car.​ Everyone like my economy answers please​

Answer 1

Answer:

An engine approaches a hill with a constant speed. When it is at a distance of 0.9km, it blows a whistle, whose echo is heard by the driver after 5s. If speed of sound in air is 330m/s, the speed of engine is

A

10m/s

B

20m/s

C

30m/s

D

40m/s

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Solution



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Correct option is C)

If the speed of engine is v, the distance travelled by engine in 5s will be 5vand hence the distance travelled by sound in reaching the hill and coming back to the moving driver

=900+(900−5v)

1800−5v

So, the time interval between original sound and it's echo

t=330(1800−5v)=5⇒v=30m/s

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SIMILAR QUESTIONS

There is a road between two parallel rows of buildings and distance between the rows of building is 106 m. The velocity of car if a car blows a horn whose echo is heard by the driver after 1 s, is :( Given: speed of sound =340 m/s)

Hard

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An engine moving away from a vertical cliff blows a horn at frequency f. Its speed is 0.5% of the speed of sound in air. The frequency of the reflected sound received at the engine is :