The frequency of a radar is 780 MHz. The frequency of the reflected wave from an aeroplane is increased by 2 .6 kHz. The velocity of aeroplane is

See questiotr (08). n′−n′′=Δn=2VsV×n Δn=2⋅6kHz=2⋅6×103Hz  and n=780MHz=780×106Hz ∴ 2⋅6×103=2VS3×108×780×106  or  vs=2⋅6×1033×1082×780×106=500m/s =0⋅5km/sec