Question 33 of 121

A person standing on an open ground hears the sound of a jet aeroplane, coming from north at an angle ${60}^{o}$ 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:

A$\dfrac{2v}{\sqrt{3}}$B$v$C$\dfrac{v}{2}$D$\dfrac{\sqrt{3}}{2}v$

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Answer: (C) $\dfrac{v}{2}$

$\dfrac{d}{{v}_{s}}=\dfrac{d cos{60}^{o}}{{v}_{a}}$

${v}_{a}=\dfrac{{v}_{s}}{2}=\dfrac{v}{2}$