In an open end organ pipe of length ' $L$ ', if the velocity of sound is ' V ', then the fundamental frequency will be (Neglect end correction)

At what speed should a source of sound move so that the observer finds the apparent frequency equal to half the original frequency?

A tuning fork gives 5 beats per second with 40 cm length of sonometer wire. If the length of the wire is shortened by 1 cm , the number of beats is still the same. The frequency of the fork is

A sound source is moving towards a stationary observer with $\left(\frac{1}{10}\right)^{\text {th }}$ the speed of sound, The ratio of apparent to real frequency is