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14. waves and sound — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics14. waves and sound1 Mark
MCQ
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 $\upsilon $ is the speed of sound, speed of the plane is
  • A
    $\frac{{\sqrt 3 }}{2}\upsilon $
  • B
    $\frac{{2\upsilon }}{{\sqrt 3 }}$
  • C
    $\upsilon $
  • ✓
    $\frac{\upsilon }{2}$
✓

Answer

Correct option: D.
$\frac{\upsilon }{2}$
d
$\mathrm{V}_{\mathrm{P}} \rightarrow$ Speed of plane

$\vee \rightarrow$ Speed of sound

$\vee \cos 60^{\circ}=V_{P}$

$V_{P}=\frac{V}{2}$

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