Question

Question 7 (b)
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:
(b) the acceleration of the train.

Answer 1

Acceleration of the train = a
The engine exerts a force of 40000 N on all the five wagons.
Net accelerating force on the wagons, $F_a$ = 35000 N
Mass of the wagons, m = Mass of a wagon $\times$ Number of wagons
Mass of a wagon = 2000 kg
Number of wagons = 5
$\therefore$ m = 2000$\times$5 = 10000 kg
Total mass, M = m = 10000 kg
From Newton's second law of motion:
$F_a$ = Ma
$a=\frac{F}{M}=\frac{35000}{10000}=3.5m{s}^{-2}$
Hence, the acceleration of the wagons and the train is $3.5m{s}^{-2}$.