Question

a moving train brought to rest within 20 seconds by applying brakes . Find the initial velocity, if the retardation due to brakes is 2 ,metre /second

Answer 1

Answer:

Initial velocity of the train

= 40 m/s

Step by step explanations :

Given that,

a moving train brought to rest within 20 seconds by applying brakes

here,

final velocity of the train = 0 m/s

let the initial velocity of the train be u

given retardation produced by the brakes = 2 m/s²

so,

acceleration = -2 m/s²

given time taken to stop = 20 seconds

now we have

Initial velocity (u) = u

final velocity(v) = 0 m/s

acceleration(a) = -2 m/s²

time taken(t) = 20 seconds

by the equation of motion,

v = u + at

putting the values,

0 = u + (-2)(20)

u - 40 = 0

u = 40 m/s

so,

Initial velocity of the train

= 40 m/s

Answer 2

$\bold {\huge {Your ~answer :-}}$

$\bf\huge\boxed{40\:m/s}$

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Given—

Time taken by train to be in rest = 20 sec

Negative acceleration(retardaction) = - 2 m/s²

Final velocity of the train = 0 m/s

To find -

Initial velocity of the train = ?

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We will apply Laws of Motion

v = u + at

Now substituting the value

⇒0 = u +(-2)×20

⇒u = 40 m/s

Hence, the initial velocity of train is 40 m/s.

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