Chapter 8

NCERT
Class 9
Science
Solutions
7. 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 after a friction force of 5000 N then calculate:

Question:

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 after a friction force of 5000 N then calculate:

(a) the net accelerating force.

(b) the acceleration of the train, and

(c) the force of wagon 1 on wagon 2

Answer:

(a) Mass of train along with wagons

     = mass of train + mass of 5 wagons

     = 8000 + 5 × 2000

     = 18000 kg

Net accelerating force = 40000 – 5000 N

                                      = 35000 N

(b) Acceleration = F/m

                           = 35000/10000

                           = 35 ms-2

(c) F = ma

        = 2000 × 1.9

        = 3800N

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