Question

Agar is moving in a straight line with the speed in kilometre per hour it is a stop in 5 seconds by applying brakes find 1. the speed of car in metre per second 2.the retardation

Answer 1

The speed of car - 5 m/s.

The retardation - 1 m/s².

Accurate Question :

A car is moving in a straight line with speed 18 km  $\bf\;h^{-1}$ . It is stopped in 5 seconds by applying the brakes. Find :

• The speed of car in $\bf ms^{-1}$
• The retardation.

Solution :

Given :

Speed - 18 km/h.

Time - 5 seconds.

$\rule{300}{1.5}$

• The speed of car in $\bf ms^{-1}$

We know :

$\bigstar\;\boxed{\bf Speed = \dfrac{Distance}{Time}}}}}$

So,

$\implies \sf 18\times\dfrac{5}{18}\\ \\ \\\implies \sf 5\;m/s.$

$\rule{300}{1.5}$

• The retardation.

Remember that Retardation means negative acceleration.

Therefore,

$\bigstar\;\boxed{\bf a= \dfrac{v-u}{t}}}}}}$

So,

$\implies \sf a= \dfrac{v-u}{t}\\ \\ \\ \implies \sf \dfrac{0-5}{5}\\ \\ \\\implies \bf 1\;m/s^2$

Answer 2

Explanation:

Correct Question -

A car is moving in a straight line with the speed 10 Km/h it is a stop in 5 seconds by applying brakes Find 1) The speed of car in metre per second 2) The retardation

Given -

Speed of car = 18 Km/h

» 18 × 1000/60×60

» 180/36

• » 5 m/s

Time = 5 seconds

To Find -

• Speed of car in m/s
• The retardation

Now,

Speed of car in m/s is 5 m/s

And

As we know that :-

• v = u + at

here,

v = final velocity

u = initial velocity

a = acceleration

t = time

» 0 = 5 + 5a

» -5 = 5a

» a = -5/5

• » a = -1 m/s²

Hence,

The speed of car in m/s is 5 m/s

And

The acceleration is -1 m/s²