Question

A 8000kg engine pulls a train of 5 wagons, each of 2000kg along a horizontal track. If the engine exerts a force of 40000N and the track offers a friction force of 5000N. Then calculate

1)the net accelerating force;

2)the acceleration of the train ;and

3) the force of wagon 1on wagon 2.

Answer 1

Mass of the engine = 8000 kg

Mass of each wagon = 2000 kg,

Np. of wagons = 5

mass of total wagon=2000×5
=10000

Total mass of train = 8000+(2000×5)=18000

Force, F = 40000 N

Track resistance , R = 5000 N

Total accelerating force = F −R
=40000−5000=35000

Let acceleration = y m/s²

Acceleration = Accelerating force / mass

y=35000/18000
​​​ = 35/18
=1.94 m/s²

Frictional resistance of 4 wagons =5000×(2000×4)/18000 =2222 .22 N

Accelerating force on 4 wagons =2000×4×1.944 =15552 N

Hence total force exertred by wagon on wagon 2= Accelerating force +Frictional resistance
=2222 .22 +15552=17774.22 N

So,

The net accelerating force=35000

The acceleration of the train=1.94 m/s²

The force of wagon 1on wagon 2=17774.22 N