A train is moving with a constant speed along a large circular track. The engine of the train emits a sound of frequency f. The frequency heard by the guard at rear end of the train :

Question

A train is moving with a constant speed along a large circular track. The engine of the train emits a sound of frequency f. The frequency heard by the guard at rear end of the train : (A) is less than f (B) is greater than f (C) is equal to f (D) may be greater than, less than or equal to f depending on the factors like speed of train, length of train and radius of circular track

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<img class="img-fluid question-image" alt="Solution" src="https://cdn.tardigrade.in/q/nta/p-cwc0mvefnnoxb95q.jpg" /> Vreal along line goining =Vtcos(90 - θ )-Vtcos(90 - θ ) = Zero ⇒ fapp=f

Q. A train is moving with a constant speed along a large circular track. The engine of the train emits a sound of frequency $f .$ The frequency heard by the guard at rear end of the train :

is less than $f$

is greater than $f$

is equal to $f$

may be greater than, less than or equal to $f$ depending on the factors like speed of train, length of train and radius of circular track

Vreal along line goining $= V_{t} cos (90 - θ) - V_{t} cos (90 - θ)$
$=$ Zero $\Rightarrow f_{a pp} = f$

Q. A train is moving with a constant speed along a large circular track. The engine of the train emits a sound of frequency f. The frequency heard by the guard at rear end of the train :

is less than f

is greater than f

is equal to f

may be greater than, less than or equal to f depending on the factors like speed of train, length of train and radius of circular track