Question

A train weighing 100 metric ton is running on a level track with a uniform speed of 72 km/h .If the frictional resistance amounts to 0.5 kg per metric ton ,find power of the engine.​

Answer 1

Answer:velocity=72×(1000÷3600)=20m/s

F=0.5×100×9.8

Power=F×v

=0.5×100×9.8×20

=9800W

=9.8 kW

Explanation: Since a=0 as speed is uniform.

Therefore,force of friction=force applied on train.

Answer 2

Answer:

Mass of the train is,

m = 105 kg

Uniform speed of the train is, u = 72 km/h = 20 m/s

Frictional force per metric ton is = 0.5 × 9.8 N = 4.9 N

Therefore, frictional force on the train = 4.9 × 100 = 490 N

Since, the train has to overcome this frictional force to maintain a constant speed, the power is given by,

Power = (force)(speed) = 490 × 20 = 9800 W