Question.
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 40000 N and the track offers a frictional 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
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 40000 N and the track offers a frictional 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
Solution:
(a) Force exerted by the engine $=40,000 \mathrm{~N}$
Force of friction exerted by the tracks $=5000 \mathrm{~N}$
As the force of friction always acts opposite to the direction of applied force,
$\therefore$ Net accelerating force of engine
$=40000-5000=35000 \mathrm{~N}$
(b) Mass of 5 wagons $=2000 \times 5=10000 \mathrm{~kg}$
We know, $\mathrm{F}=\mathrm{ma}$
or $35000=10000 \times$ a
$\Rightarrow \quad a=\frac{35000}{10000}=3.5 \mathrm{~m} / \mathrm{s}^{2}$
(c) Force of wagon 1 on wagon $2=$
mass of 4 wagons behind wagon $1 \times$
acceleration
$\mathrm{F}=4 \times 2000 \times 3.5=28000 \mathrm{~N}$
(a) Force exerted by the engine $=40,000 \mathrm{~N}$
Force of friction exerted by the tracks $=5000 \mathrm{~N}$
As the force of friction always acts opposite to the direction of applied force,
$\therefore$ Net accelerating force of engine
$=40000-5000=35000 \mathrm{~N}$
(b) Mass of 5 wagons $=2000 \times 5=10000 \mathrm{~kg}$
We know, $\mathrm{F}=\mathrm{ma}$
or $35000=10000 \times$ a
$\Rightarrow \quad a=\frac{35000}{10000}=3.5 \mathrm{~m} / \mathrm{s}^{2}$
(c) Force of wagon 1 on wagon $2=$
mass of 4 wagons behind wagon $1 \times$
acceleration
$\mathrm{F}=4 \times 2000 \times 3.5=28000 \mathrm{~N}$