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
a) the net accelerating force.
b) the acceleration of the train and
c) the force of wagon $1$ on wagon $2$.

Answer 1

a) Net accelerating force = Force exerted by engine – Frictional force.

(Here the frictional force is subtracted because it opposes the motion)

$=40000–5000=35000N$

$=3.5\times 104N$.

b) From Newton’s second law of motion,

Accelerating force = mass of the train * Acceleration of train,

$a=\frac{F}{m}$

Mass of train = Mass of engine + Mass of all wagons,

$=8000+5\times 2000$

$=8000+10000$

$=18000Kg$.

$\therefore$ Acceleration $=\frac{35000}{18000}=\frac{35}{18}$

$=1.95m{s}^{-2}$.

c) Force of wagon $1$ on wagon $2$

= Mass of the engine * Acceleration,

$=800\times 1.95=15600N$.