The frequency of a source of sound is 100 Hz. How money times does it vibrate in a minute?

A train whistling while approaching a railway platform with a speed of 90 km(s)^-1 .The frequency of sound of the whistle is 600 Hz.If the velocity of sound in air is 325 m(s)^-1 ,calculate the apparent frequency of the sound of the whistle as heard by an observer standing on the platform.

Show by two neat diagrams that the frequency of the first overtone of vibrating air coloumn in a organ pipe open at one end is three times the frequency of its fundamental vibration.

Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440m/s in a given medium'.

A frequency of the horn of a car drops from 280 Hz to 240 hz as the car passes a stationary observer.What is the speed of the car?[velocity of the sound in the air is 330 m(s)^-1].