Example 12: A 1000 kg engine pulls a train of 4 wagons each of 2500 kg along a horizontal railway track. If the engine exerts a force of 50000 N on wagons and track offers a force of fiction of 2500 N on each wagon, then calculate (i)The net accelerating force (ii) the acceleration of the train (iii) the force by Wagon 1 on wagon 2
Answers
Answer:
Given parameters
Mass of the engine = 8000 kg
Number of wagons = 5
Mass of the wagons = 2000 kg
Force exerted by the engine (F ) = 40000 N
Frictional force offered by the track (Ff) = 5000 N
(a) Net accelerating force (Fa) = F – Ff
Fa = 40000 N – 5000 N
Fa = 35000 N
(b) Let us consider the acceleration of the train be a m/s2
Acceleration is the ratio of net acceleration force by mass, i.e
a = Fa/m
Where m is the mass of the train, it can be calculated as follows
Total mass of the train (m) = Mass of the engine + (Mass of the wagons + Number of wagons)
m = 8000 + (5 × 2000)
m = 18000 kg
Acceleration of the train (a) = 35000/18000
a = 1.944m/s2
(c) Force of wagon 1 on wagon 2 = 4 × mass of wagon × a
Force of wagon 1 on wagon 2 = 4 × 2000 × 1.944
Force of wagon 1 on wagon 2 = 15552 N
Answer: