Microwaves which travel with the speed of light are reflected from a distant aeroplane approaching the wave source radar. It is found that when the reflected waves are beat against the waves radiated

Question

Microwaves which travel with the speed of light are reflected from a distant aeroplane approaching the wave source radar. It is found that when the reflected waves are beat against the waves radiated from the source, the beat frequency is 990 Hz. If the microwaves are 0.1 m in wavelength, what is the approaching speed of the aeroplane? (answer in $m/s$ ).

Answer:

49.50

Solution:

The reflected frequency shifts by $Δ f = 2 u f / c = 2 u / λ$ . So $u = Δ f λ /2 = 990 \times 0.1/2 = 49.5$ m/s.

TestHub · Accepted Answer

The reflected frequency shifts by Δ f = 2 u f / c = 2 u / λ . So u = Δ f λ /2 = 990 × 0.1/2 = 49.5 m/s.

Physics - Sound Wave Question with Solution | TestHub

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