Question

A train starts from rest and accelerates uniformly for 20 sec to attain a velocity of 90km/h.Find its acceleration

Answer 1

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The initial velocity of the train(u)= 0km/h(train starts at rest)

The final velocity of the train= 90km/h

time its take to accelerate = 20sec = 20/3600

= 1/180 h

the acceleration takes place

=( v - u )/t

= (90-0) / (1/180)

= 90 ×180

= 16200km/h²

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Answer 2

Answer:

Explanation:

Given :-

Initial velocity of train, u = 0 (As train starts from rest)

Final velocity of train, v = 90 km/h = 90 × 5/18 = 25 km/h

Time taken by train, t = 20 seconds

To Find :-

Acceleration by train, a = ??

Formula to be used :-

1st equation of motion, i.e,

v = u + at

Solution :-

Putting all the values, we get

v = u + at

⇒ 25 = 0 + a × 20

⇒ 25 = 20a

⇒ 25/20 = a

⇒ a = 1.25 m/s²

Hence, the acceleration by train is  1.25 m/s².