Question

A train of mass 200tons moving with a speed of 36kmph switches the engine and comes to rest in 0.5km.Find the resistance offered​

Answer 1

Correct question:-

A train of mass 200 tons moving with a speed of 36km/h switches off the engine and comes to rest in 0.5km.Find the resistance offered.

Given:-

→Mass of the train=200 tons

→Initial velocity of the train=36km/h

→Final velocity of the train=0

→Distance covered=0.5km

To find:-

→Resistance offered/Resistive force

Solution:-

Firstly,we shall convert the units:-

•1 ton=1000kg

=>200ton=1000×200

=>200000kg (mass of the train)

•1km/h=5/18 m/s

=>36km/h = 5/18×36

=>10m/s. (initial velocity of the train)

•1km=1000m

=>0.5km=0.5×1000

=>500m

We shall use the 1st equation of motion to find acceleration of the train.

=>v²-u²=2as

=>0-(10)²=2×a×500

=>-100=1000a

=>a= -100/1000

=>a= -0.1m/s²

Thus,we got acceleration of the train

as -0.1m/s².

Now,we shall use Newton's 2nd law of motion to find the resistive force.

=>F=ma

=>F=200000×(-0.1)

=>F= -20000N

Thus,resistance offered is 20000N.