Question

) An Engine applies 800 N of force to run a train of 5 wagons. How much should be the frictional force
exerted to stop the train?
a. 800 N b. 4000 N c. -850 N d. 0N

Answer 1

Answer:

9 Scienceexcellup logo

Force and Laws of Motion

NCERT Exercise Solution - part 2

Question 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 offers 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: Given, force of engine = 40000 N

Force of friction = 5000 N

Mass of engine = 8000 kg

Total weight of wagons = 5 x 2000 kg = 10000 kg

(a) The net accelerating force

= Force exerted by engine – Force of fricition

= 40000 N – 5000 N = 35000 N

(b) The acceleration of the train

We know that, F = mass x acceleration

Or, 35000 N = (mass of engine + mass of 5 wagons) X a

Or,

35000

N

=

(

8000

k

g

+

10000

k

g

)

×

a

Or,

35000

N

=

18000

k

g

×

a

⇒

a

=

35000

N

18000

k

g

=

1.944

m

s

−

2