Question

A moving Train is brought to rest within 20seconds by applying brakes. Find the initial velocity if the retardation due to brakes is 1.5metre second square

Answer 1

Answer:

30 m/s

Explanation:

According to the given question,

t = time = 20 sec

a = acceleration and -a = deceleration

-a = 1.5 m/s^2 or a = -1.5 m/s^2

v = final velocity = 0 m/s

u = intial velocity = ?

And we are asked to find the initial velocity of the moving train.

We know,

• v = u+at

Putting the values we get,

• 0 = u -1.5×20

• 0 = u-15×2

• 0 = u-30

• u = 30 m/s

Thus intial velocity of the train is 30 m/s from the given data.

Answer 2

$\huge \red { \boxed{ \boxed{ \mathsf{ \mid \ulcorner Answer : \urcorner \mid }}}}$

Time (t) = 20 s

final velocity (v) = 0

retardation (- a) = 1.5 m/s²

============================

Use equation :-

v = u + at

____________[Put Values]

0 = u +(-1.5)(20)

0 = u - 30

u = 30

$\huge{\sf{u \: = \: 30 \: m \: s^{-1}}}$