Shock Wave Of Jet Plane

Classical Mechanics Level 2

The above is a schematic diagram of the shock wave of a jet plane (the sound source) which is flying at a constant velocity of $v_s.$ When the sound source moves from $S_1$ to $S_2$ , the sound wave which was generated at $S_1$ progresses a distance of $R$ as above. Which of the following explanations is correct? (The velocity of sound is $v$ .)

a) $v_s$ is larger than $v$ .

b) The distance between $S_1$ and $S_2$ is $\frac{v_sR}{v}$ .

c) If $v_s$ becomes bigger, then $\theta$ becomes bigger, too.

a) and c) a) only a), b) and c) a) and b)

8 solutions

Ahmed Shaltoot
Mar 8, 2014

as obvious :-

the sound source (jet) traveled a distance larger than that of sound, that is, distance between S1, S2 > R .........Jet is out of sound propagation sphere. *............the time is the common distance traveled by jet = vs.t
.........distance traveled by sound R = v * t .....t= R/v ..........distance (S1 -> S2) = vs * R/v

R/V=D/Vs
tan(theta)=R/D=V/Vs

Abhijit Bhowmik - 7 years, 3 months ago

up :D

Alvin Reyes - 7 years, 3 months ago

D Biswas
Apr 16, 2014

since the tym take for the wave to travel R is the same as the time taken to travel S1S2.....teh solution is easily obtained.........hence B) is true.....A) is obviously true.....nd C) is wrong as wid increase in Vs.... thita would decrease......its better to visualise dis than to rely on hard core maths. .

Bryan Dellariarte
Mar 24, 2014

self explanation.. hehehe

Karen Adelan
Mar 10, 2014

self explanation

Ashwin Shridhar
Mar 10, 2014

Elementary level Gas Dynamics Problem The distance S1S2 can be easily found out using the relation sin(theta)=1/M where M is mach number vs/v also the flow is supersonic so clearly vs>v and since sin(theta) has an inverse relation with mach number M so as theta increases vs decreases. so answer is a and b.

Krishna Das
Mar 9, 2014

The wave front of a supersonic object will be conical with the object at the apex. sin(theta)=V t/Vs t, where theta is the semi vertical angle of the cone

Aniruddho Ray
Mar 8, 2014

a)since S1S2>R, Vs>V b)since time taken by both the jet and the sound wave is the same, S1S2/Vs=R/V.so S1S2=RVs/V c)if theta increases so does R(according to fig.).but R depends on V not on Vs. So theta does not increase with Vs. thus the ans is (a) & (b)

Muhammad Abdul Qawi
Mar 8, 2014

b) is correct as VsR/V= distance between S1 and S2

c) is wrong as tetha becomes smaller as Vs increases so the right option is

a) and b)

looks fine

Zaheer Lone - 7 years, 3 months ago

wat s tetha?

حاتم محمد - 7 years, 3 months ago

theta as symbol of angle

Hafizh Ahsan Permana - 7 years, 2 months ago

Shock Wave Of Jet Plane

8 solutions

0 pending reports