An 8000 kg engine pulls a train of 5 wagons, each of 2000 kg, along

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

a) Net accelerating force = 40000 - 5000 = 35000 N
b) Acceleration = Force/Mass = 35000/(8000 + 5x2000) = 1.94 m/s2
c) Let’s imagine the wagon 1 and engine detached, and a force p is included to account for the detachment.
Then the net force acting, p which is acting from wagon 2 onto 1 and is same as acting from 1 to 2.
p = ma = (8000 + 2000) (1.94) = 19400 N.
Hence the force of wagon 1 on 2 is 19400 N.