A 8000 kg engine pulls a train of 5 wagons, each of 2000 kg along a horizontal track. If the engine exerts a force of 40000 N and the track offers a friction force of 5000 N, then calculate
(a) The net accelerating force
(b) The acceleration of the train
(c ) The force of wagon 1 on wagon 2.

Explanation

Force exerted by the engine, F=40000N. Frictional force offered by the track `F_f=5000N`. Net accelerating force ,`Fa=F-F_f`
=40000-5000
=-35000N
Hence , the net accelerating force is 35000N .
Acceleration of the train =a
The engine exerts a force of 40000N on all the five wagons.
Net acceleration force on the wagons=Fa=35000N
Mass of the wagons, m=Mass of a wagon x number of wagons
Mass of a wagon =5
`m 2000xx5 =10000 kg`
Total mass M=m=10000 kg
From Newton.s second law of motion
`F_a=M_a`
`a=F_(am)=[35000xx1000=3.5 ms^(2)]`
Hence the acceleration of the wagons and the train is `3.5 m//s^2`
Mass of all the wagons except wagon 1 is `4 xx 2000 =8000 kg`
Acceleration of the wagons `=3.5 m//s^2`
Thus , force exerted on all the wagons except wagon 1
`=8000 xx3.5 =28000 N`
Therefore , the force exerted by wagon 1 on the remaining four wagons is 28000N,.
Hence , the force exerted by wagon 1 on Wagon 2 is 28000 N.