3. A train moves along a straight track with constant acceleration. Three telegraph poles are set at equal intervals beside the track at points \(A , B\) and \(C\), where \(A B = 50 \mathrm {~m}\) and \(B C = 50 \mathrm {~m}\). The front of the train passes \(A\) with speed \(22.5 \mathrm {~m} \mathrm {~s} ^ { - 1 }\), and 2 s later it passes \(B\). Find

1. the acceleration of the train,
2. the speed of the front of the train when it passes \(C\),
3. the time that elapses from the instant the front of the train passes \(B\) to the instant it passes \(C\).