Question

Source and observer both are moving towards the wall with velocities vs and v0 respectively. The wall is moving away with velocity u. Air is blowing with a velocity va towards the wall. The velocity of sound w.R.T. To air is v. If frequency of sound emitted by source is n0 then frequency of reflected waves received by the observer is

Answer 1

A Doppler radar uses reflected microwaves to determine the speed of distant moving objects. It does this by sending out waves with a particular frequency, and then analysing the reflected wave for frequency changes. ... Medical imaging also makes use of the Doppler effect to monitor blood flow through vessels in the body.