Question

initial velocity of a car is 20 kilometre per hour and final velocity of it is 120 kilometre per hour it takes 20 seconds then find about the acceleration​

Answer 1

Given :-

• Initial velocity (u) = 20km/h
• Final velocity (v) = 120km/h
• Time taken (t) = 20s

To find :-

• Acceleration (a)

Solution :-

• Initial velocity = 20km/h

→ u = 20 × 5/18

→ u = 5.5m/s

• Final velocity = 120km/h

→ v = 120 × 5/18

→ v = 33.3m/s

According to the first equation of motion

→ v = u + at

→ 33.3 = 5.5 + a*20

→ 33.3 - 5.5 = 20a

→ 27.8 = 20a

→ a = 27.8/20 = 1.39m/s²

Hence,

• Acceleration of a car is 1.39 m/s²

Extra Information :-

• s = ut + ½ at² (second equation of motion)
• v² = u² + 2as (third equation of motion)
• S.I unit of velocity is m/s

Answer 2

Explanation:

$\bf{\underline{\underline\red{Given:-}}}$

• Initial velocity = 20km/h

• Final velocity = 120km/h

• Time = 20sec

$\bf{\underline{\underline\blue{To\: Find:-}}}$

• The acceleration of the car.

$\bf{\underline{\underline\green{Solution:-}}}$

Initial velocity = 20km/h

Converting 20km/h to m/s

$= 20 \times \dfrac{5}{18}$

= 5.5

Initial velocity = 5.5m/s

Final velocity = 120km/h

Converting 120km/h to m/s

$= 120 \times \dfrac{5}{18}$

= 33.3

Final velocity = 33.3m/s

As we are asked to find the acceleration of the car.

According to the second equation of motion

$\boxed{ \rm \leadsto v = u + at}$

Here:-

• v = final velocity = 5.5m/s

• u = initial velocity = 33.3m/s

• a = acceleration = ?

• t = time = 20 sec

Substituting the values:-

${ \rm \implies v = u + at}$

${ \rm \implies 33.3= 5.5 + a(20)}$

${ \rm \implies 33.3= 5.5 + 20a}$

${ \rm \implies 33.3 - 5.5 = 20a}$

${ \rm \implies 27.8 = 20a}$

${ \rm \implies \dfrac{27.8}{20} = a}$

${ \rm \implies 1.39 = a}$

${ \rm \implies a = 1.39 }$

$\boxed{ \rm \therefore Acceleration \: of \: the \: car = 1.39m/{s}^{2} }$