question_answer

A person standing on an open ground hears the sound of a jet aeroplane, coming from north at an angle \[60{}^\circ \] with ground level. But he finds the aeroplane right vertically above his position. If v is the speed of sound, speed of the plane is [JEE Main Online Paper Held On 12-Jan-2019 Morning]

A) v                                             

B) \[\frac{\sqrt{3}}{2}v\]

C) \[\frac{2v}{\sqrt{3}}\]                           

D)   \[\frac{v}{2}\]

Correct Answer: D

Solution :

\[{{v}_{p}}=v\,\cos {{60}^{o}}\]\[=\frac{v}{2}\]