A) \[15.5\,m{{s}^{-1}},\ 200\,Hz\]
B) \[19.5\,m{{s}^{-1}},\ 205\,Hz\]
C) \[29.5\,m{{s}^{-1}},\ 200\,Hz\]
D) \[32.5\,m{{s}^{-1}},\ 205\,Hz\]
Correct Answer: C
Solution :
When train is approaching frequency heard by the observer is \[{{n}_{a}}=n\,\left( \frac{v}{v-{{v}_{S}}} \right)\] Þ\[219=n\,\left( \frac{340}{340-{{v}_{S}}} \right)\] ?(i) when train is receding (goes away), frequency heard by the observer is \[{{n}_{r}}=n\,\left( \frac{v}{v+{{v}_{s}}} \right)\] Þ \[184=n\left( \frac{340}{340+{{v}_{s}}} \right)\] ?(ii) On solving equation (i) and (ii) we get \[n=200Hz\] and \[{{v}_{S}}=29.5m/s.\]
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