A train approaches stationary observer, the velocity of train being `1/20` of the velocity of sound. A sharp blast is blown with the whistle of the engine at equal intervals of 1s. The interval between the successive blasts as heard by the observer

Afrain approaches a stationary observer, the velocity of train being (1/20)th of the velocity of sound. A sharp blast is blown with the whistle of the engine at equal intervals of a second. Find the interval between the successive blasts as heard by the observer.

An observer is approaching a stationary source with a velocity 1/4 th of the velocity of sound. Then the ratio of the apparent frequency to actual frequency of source is

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

One train is approaching an observer at rest and another train is receding him with same velocity 4 ms^(-1) . Both the trains blow whistles of same frequency of 243 Hz. The beat frequency in Hz as heard by the observer is (speed of sound in air= 320ms^(-1) )

A sound source emitting sound of frequency 450 Hz is approaching a stationary observer with velocity 30 ms^(-1) and another identical source is going away from the observer with the same velocity. If the velocity of sound is 330 ms^(-1) , then the difference of frequencies heard by observer is