Question

Calculate the initial velocity of a train which is stopped in 50 seconds by applying breaks. The retardation is 5m/s^2.

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Answer 1

Answer:

Given :-

A train which is stopped in 50 seconds by applying breaks.

The retardation is 5 m/s².

To Find :-

What is the initial velocity of a train.

Formula Used :-

\boxed{\bold{\large{u\: =\: v\: -\: at}}}

u=v−at

where,

u = Initial velocity

v = Final velocity

a = Acceleration

t = Time

Solution :-

Given :

Acceleration = 5 m/s²

Time = 50 seconds

Final velocity = 0 m/s

According to the question by using the formula we get,

⇒ u = v - at

⇒ u = 0 - (5) × 50

⇒ u = - 5 × 50

➥ u = - 250 m/s

We can't take initial velocity as negative.

\therefore∴ The initial velocity of a train is 250 m/s .

Answer 2

Answer:

Initial velocity, u=?

Final velocity, v=0m/s (car is stopped)

Acceleration, a=−2.5m/s

2

(negative because it is retardation)

Time, t=10s

Use the relation of the first equation of motion:

v=u+at

0=u+(−2.5)×10

u=25m/s