A police car travels towards a stationary observer at a speed of 15 `m//s`. The siren on the car emits a sound of frequency 250 Hz. Calculate the recorded frequency. The speed of sound is 340 `m//s`.

A drone fitted with siren in flying directly away from the drone operator and towards a distant building at a speed of 15 m//s . The siren produces sound of frequency 780 Hz. What is the frequency that the operator hears in the echo reflected from the building (Speed of sound is 340 m//s ).

A source of sound is travelling towards a stationary observer. The frequency of sound heard by the observer is of three times the original frequency. The velocity of sound is v m/s. The speed of source will be

A source of sound when moves towards a stationary observer, then frequency of the sound heard by listener is more than actual frequency because the

A resonance air column of length 20 cm resonates with a tuning fork of frequency 250 Hz . The speed of sound in air is

An observer moves towards a stationary source of sound with a speed 1//5^(th) of the speed of sound. The wavelength and frequency of the source emitted are X and f respectively. The apparent frequency and wavelength recorded by the observer are respectively

A source of sound S is moving with a velocity 50 m//s towards a stationary observer. The observer measures the frequency of the source as 1000 Hz. What will be the apparent frequency of the source when it is moving away from the observer after crossing him? The velocity of sound in the medium is 350 m//s .

A tuning fork of frequency 170 Hz produces sound wave of wavelength 2m. Calculate speed of sound.

A man is watching two trains, one leaving and the other coming in with equal speeds of 4 m//s . If they sound their whistles, each of frequency 240 Hz, the number of beats heard by the man (velocity of sound in air = 320 m//s ) will be equal to

Two cars are moving on two perpendicular roads towards a crossing with uniform speeds of 72 km/hr and 36 km/hr. If first car blows horn of frequency 280 Hz, then the frequency of horn heard by the driver of second car when line joining the cars make 45^@ angle with the roads will be