Question

A car is moving at a speed of 20km/hr the driver acclerates the car and speed increases to 30km/hr in 5 sec ? Calculate accleration​

Answer 1

Answer :

Initial speed = 20km/hr

Final speed = 30km/hr

Time interval = 5s

We have to find acceleration of car.

$\star$ Acceleration is defined as the rate of change of velocity/speed.

• a = (v - u) / t

It is a vector quantity having both magnitude as well as direction.

It can be positive, negative or zero.

SI unit : m/s

$\star$ Conversion :

• 1 km/hr = 5/18 m/s

➝ 20 km/hr = 20 × 5/18 = 5.55 m/s

➝ 30 km/hr = 30 × 5/18 = 8.33 m/s

$\star$ Calculation :

⭆ a = (v - u) / t

⭆ a = (8.33 - 5.55) / 5

⭆ a = 2.78/5

⭆ a = 0.556 m/s²

Answer 2

Given:

A car is moving at a speed of 20km/hr, the driver acclerates the car and speed increases to 30km/hr in 5 sec.

To find:

Acceleration of the car.

Calculation:

Acceleration is defined as the instantaneous rate of change of velocity with respect to time. Since the car is moving in a single direction, Velocity and Speed can be used synonymously.

First , we need to convert unit of Velocity from km/hr to m/s :

$1) \: 20 \: km/hr = 20 \times \dfrac{5}{18} = 5.55 \: m/s$

$2) \: 30 \: km/hr = 30 \times \dfrac{5}{18} = 8.33\: m/s$

Applying 1st equation of Kinematics:

$\therefore \: v = u + at$

$= > \: 8.33= 5.55 + a(5)$

$= > \:5a = 2.78$

$= > \:a =0.556 \: m/ {s}^{2}$

So, acceleration of car is 0.556 m/s².