A train has arrived into a track which is a semicircle. At an instant when the engine is at the forward end of the semi circular part of the track while the last carriage is at the rear end, the driver blows a whistle of frequency 200 Hz. Velocity of sound is 340 m/sec. Then the apparent frequency as observed by a passenger in the middle of the train at the same instant is, (the speed of the train is 30 m/second)
A train has arrived into a track which is a semicircle. At an instant when the engine is at the forward end of the semi circular part of the track while the last carriage is at the rear end, the driver blows a whistle of frequency 200 Hz. Velocity of sound is 340 m/sec. Then the apparent frequency as observed by a passenger in the middle of the train at the same instant is, (the speed of the train is 30 m/second)
The correct option is C 200 Hz
The situation is shown in the fig.
But the source (engine) and the observer (Person in the middle of the train) have the same
speed, but their direction of motion is right angles to each other. The component of velocity of
observer towards source is v cos 45∘ and that of source along the line joining the observer and
source is also vcos 45∘. There is no relative motion between them and therefore no change in
frequency heard. The frequency heard is 200 Hz.
200 Hz
The situation is shown in the fig.
But the source (engine) and the observer (Person in the middle of the train) have the same
speed, but their direction of motion is right angles to each other. The component of velocity of
observer towards source is v cos 45∘ and that of source along the line joining the observer and
source is also vcos 45∘. There is no relative motion between them and therefore no change in
frequency heard. The frequency heard is 200 Hz.
