A car passing a check post gives sound of frequency 1000 c.p.s. If the velocity of the car is `72km//h` and of sound is `350m//s` , find the change is apparent frequency as it crosses the post.

A train moving at 40 m/s, passes by a stationary observer, emitting a whistle of frequency 300 Hz. If the velocity of sound wave is 340 m/s, then the change in the apparent frequency of the sound, just before and after the train passes by the observer will be nearly

A source of sound is travelling with a velocity 40 km / hour towards observer and emits sound of frequency 2000 Hz . If velocity of sound is 1220 km / hour , then what is the apparent frequency heard by an observer

A car is moving along X-axis with a velocity v=20m//s . It sounds a whistle of frequency 660 Hz. If the speed of sound is 340m//s . The apparent frequency heard by the observer O (shown in figure) is:

The driver of a car travelling with a speed of 30 m/s towards a wall sounds a siren of frequency 500 Hz. If the velocity of sound in air is 330 m/s, then the frequency of the sound reflected from the wall and as heard by the driver is

A car, sounding a horn of frequency 1000 Hz, is moving directly towards a huge wall at a speed of 15 m/s. If speed of sound is 340 m/s, then the frequency of the echo heard by the driver is

A source of sound and a listener are moving towards each other . The velocity of the source is 20 m s^(-1) and that of the observer is 15 m s^(-1) . If the velocity of sound is 340 m s^(-1) and its frequency is 640 Hz, find the apparent frequency of the sound .