5 A train consists of an engine and five carriages. A constant resistance force of 3000 N acts on the engine, and a constant resistance force of 400 N acts on each of the five carriages.
The maximum speed of the train on a horizontal track is \(90 \mathrm {~km} \mathrm {~h} ^ { - 1 }\).
- Show that this speed is \(25 \mathrm {~m} \mathrm {~s} ^ { - 1 }\).
- Hence find the maximum power output of the engine. Give your answer in kilowatts.
(3 marks)