or u a al.syl w=f.s P- tals significant figures. u DTo enable a train to travel at a Steady speed of 30 ms-1 along a level track, the engine P=kv must supply a pulling force of 50 kN. (a) How much work is the engine doing every second? (b) If the power is proportional to the cube of the velocity, how much power is needed to drive the train at a speed of 40 ms-1? 200 ms-1 up an inclined road ) EN