A person standing on an open ground hears the sound of a jet aeroplane, coming from north at an angle 60° 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 :

Question

A person standing on an open ground hears the sound of a jet aeroplane, coming from north at an angle 60° 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) (2 upsilon/√3) (B)  upsilon (C) ( upsilon/2) (D) (√3/2) upsilon

Tardigrade Admin · Accepted Answer

AB =Vp× t BC = Vt cos60° = (AB/BC) (1/2) = (Vp× t/Vt) Vp = (V/2)

Q. A person standing on an open ground hears the sound of a jet aeroplane, coming from north at an angle $6 0^{\circ}$ with ground level. But he finds the aeroplane right vertically above his position. If $υ$ is the speed of sound, speed of the plane is :

$\frac{2 υ}{3}$

$υ$

$\frac{υ}{2}$

$\frac{3}{2} υ$

$A B = V_{p} \times t$
$BC = V t$
$cos 6 0^{\circ} = \frac{A B}{BC}$
$\frac{1}{2} = \frac{V _{p} \times t}{V t}$
$V_{p} = \frac{V}{2}$

Q. A person standing on an open ground hears the sound of a jet aeroplane, coming from north at an angle 60∘ with ground level. But he finds the aeroplane right vertically above his position. If υ is the speed of sound, speed of the plane is :

3​2υ​

υ

2υ​

23​​υ

AB=Vp​×t BC=Vt cos60∘=BCAB​ 21​=VtVp​×t​ Vp​=2V​

Q. A person standing on an open ground hears the sound of a jet aeroplane, coming from north at an angle $6 0^{\circ}$ with ground level. But he finds the aeroplane right vertically above his position. If $υ$ is the speed of sound, speed of the plane is :

$\frac{2 υ}{3}$

$υ$

$\frac{υ}{2}$

$\frac{3}{2} υ$

$A B = V_{p} \times t$
$BC = V t$
$cos 6 0^{\circ} = \frac{A B}{BC}$
$\frac{1}{2} = \frac{V _{p} \times t}{V t}$
$V_{p} = \frac{V}{2}$