Question

A car accelerates uniformly from 18 km/h to 36 km/h in 5 minutes. The acceleration is

(a) 5 km/h2

(b) 1 km/ s2

(c) 216 m/s2

(d) 216 km/h2​

Answer 1

Given:-

→Initial velocity of the car=18km/h

→Final velocity of the car=36km/h

→Time taken=5 minutes

To find:-

→Acceleration of the car

Solution:-

Firstly,let's convert the time from minutes to hour.

=>1min= 1/60h

=>5min= 5(1/60)h

=>1/12h

By using the 1st equation of motion,we get:-

=>v=u+at

=>a=v-u/t

Where:-

•a is acceleration of the body

•v is final velocity of the body

•u is initial velocity of the body

•t is time taken

=>a= 36-18/(1/12)

=>a= 18/(1/12)

=>a = 18(12)

=>a = 216km/h²

Thus, acceleration of the car is 216km/h²,and hence the correct option is (d).

Some Extra Information:-

Acceleration:

•Acceleration of a body is the change in velocity of the body per unit time.

•Acceleration=Change in Velocity/Time interval

•The S.I unit of acceleration is m/s². Other units are km/h²,cm/s².

•Negative acceleration is called deceleration/retardation.

Answer 2

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$\Large\fbox{\color{purple}{QUESTION}}$

A car accelerates uniformly from 18 km/h to 36 km/h in 5 minutes.

The acceleration is

(a) 5 km/h2

(b) 1 km/ s2

(c) 216 m/s2

(d) 216 km/h2

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$\bf\Huge\red{\mid{\overline{\underline{ ANSWER }}}\mid }$

Given,

u=18 $\frac{km}{hr}$

= $\frac<strong>{</strong><strong>18×1000</strong><strong>}</strong><strong>{</strong><strong>6</strong><strong>0</strong><strong>×</strong><strong>6</strong><strong>0</strong>}$

=5m/s

v=36 $\frac{km}{hr}$

= $\frac<strong>{</strong><strong>36×1000</strong>}{<strong>6</strong><strong>0</strong><strong>×</strong><strong>6</strong><strong>0</strong>}$

=10m/s

t=5sec

acceleration, a=?

1st equation of motion,

v=u+at

10=5+5a

5a=5

a= $\frac{<strong>5</strong>}{<strong>5</strong>}$

=1m/s