Question

A car approaching a crossing at a speed of 20 ms, sounds a horn of frequency 500 Hz
when 80 m from the crossing, Speed of sound in air 330 ms. What frequency is heard by
an observer 60 m from the crossing on the straight road which crosses car road at right
angles?
(u) 525 Hz (b) 515 Hz
(@) 510 Hz
(d) 530 Hz​

Answer 1

Answer:

Option(A). 525Hz

In dopplers effect, when we need to consider velocities of source and observer along the line joining source and observer.

So at the given instant,

We need to take velocity component of car along the line joining observer and car(source)

Please check the attached pic for the solution.