Two train travelling in opposite directions at 126 km/hr each, cross other while one of them is whistling if the frequency of the node is 2.22 kHz find the apparent frequency as head by an observer in the other train :
(a) Before the trains cross each other
(b) After the trains have crossed each other `(V_("sound") = 335 m//sec)`

Explanation

To solve the problem, we need to find the apparent frequency of the whistle heard by an observer in the other train in two scenarios: before the trains cross each other and after they have crossed each other.

### Given Data:
- Speed of each train, \( V_1 = 126 \, \text{km/hr} \)
- Frequency of the whistle, \( f = 2.22 \, \text{kHz} = 2220 \, \text{Hz} \)
- Speed of sound, \( V = 335 \, \text{m/s} \)

### Step 1: Convert the speed of the train from km/hr to m/s
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