Q: Find the power of an engine which can draw a train of 400 metric ton up the inclined plane of 1 in 98 at the rate 10 m/s. The resistance due to friction acting on the train is 10 N per ton.

Sol: Given sin θ = 1/98 ; m = 400 × 10^{3} kg

Frictional force f = 10 × 400 = 4000 N ;

Velocity v = 10 m/s

∴ power P = (mg sinθ + f) v

∴ P = [(400 × 10^{3} × 9.8 × 1/98)+ 4000] × 10

= 440000 W = 440 KW