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
Medium
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Veral along line goining
$ = {V_t}\cos \,\,\left( {90 - \theta } \right) - {v_t}\cos \,\,\left( {90 - \theta } \right)$
$=$ Zero $ \Rightarrow {f_{app}} = f$
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