A 1000 kg engine pulls a train of 4 wagons each of 2500 kg along a horizontal railway track . If the engine exerts a force of 50000 N on wagons and track offers force of friction 10000 N, then calculate
(i) The net accelerating force
(ii) The acceleration of the train
(iii) The force of wagon -1 on wagon - 2

Explanation

Force exerted by the engine is `F_(1)=50,000 N `
Frictional force exerted by the track, `F_(2)= -10000 N`
Negative sign shows that friction is opposite to the direction of motion.
(i) Therefore, net accelerating force `(vecF)=vecF_(1)+vecF_(2)`
`=50,000 +(-10,000)`
`=40,000 N`
(ii) Mass of each wagon of the train = 2500 kg
Number of wagons of the train = 4
`therefore underset("(without engine)") ("Mass of the train(m)")=2500 xx 4=10,000 kg`
Net accelerating force acting on the train is
F = 40,000 N
From,
F = ma
`a=(F)/(m)=(40,000)/(10,000)=4m//s^(2)`
(iii) Mass of one wagon `(m_(1))=2500 kg`
Acceleration of the train `a=4m//s^(2)`
Force exerted by wagon-1 on wagon-2 is the accelerating force for the three rear wagons.

`therefore F'=3xx2500 xx 4m//s^(2)`
`=30,000N`