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A engine is approaching a hill at consta...

A engine is approaching a hill at constant speed. When it is at a distance of `0.9 km`, it blows a whistle, whose echo is heard by the driver after `5 s`. If the speed of sound is `340 m//s`, calculate the speed of the engine.

A

`10 m//s`

B

`20 m//s`

C

`30 m//s`

D

`40 m//s`

Text Solution

Verified by Experts

The correct Answer is:
C

`(900 + 900 - u t)/(v) = t`
`1800 = (u + v)t`
`=(u+330) xx 5`
`u = 30 m//s`
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