Question

a car breaks a speed of 108km/hr to 72km/hr during a displacement of 100m
what is its acceleration​

Answer 1

Answer:

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Answer 2

Answer :

➥ The acceleration of a car = -2.5 m/s²

Given :

➤ Intial velocity of a car (u) = 108 km/hr

➤ Final velocity of a car (v) = 72 km/hr

➤ Displacement of a car (s) = 100 m

To Find :

➤ Acceleration of a car (a) = ?

Solution :

◈ Intial velocity (u) = 108 km/hr = 108 × 5/18 = 30 m/s

◈ Final velocity (v) = 72 km/hr = 72 × 5/18 = 20 m/s

Acceleration of a car

From third equation of motion

$\tt{:\implies {v}^{2} = {u}^{2} + 2as}$

$\tt{:\implies 20 \times 20 = 30 \times 30 + 2 \times a \times 100}$

$\tt{:\implies 400 = 900 + 2 \times a \times 100}$

$\tt{:\implies 400 = 900 = 200a}$

$\tt{:\implies 400 - 900 = 200a}$

$\tt{:\implies - 500 = 200a}$

$\tt{:\implies \cancel{\dfrac{- 500}{200}} = a }$

$\bf{:\implies \underline{ \: \: \underline{ \purple{ \: \: a = - 2.5 \: m/s^2 \: \: }} \: \: }}$

Hence, the acceleration of a car is -2.5 m/s².

⠀⠀

Additional Information :

What is acceleration ?

➜ Acceleration is a vector quantity that is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity.

What is Instantaneous acceleration ?

➜ The ratio of change in velocity during a given time interval such that the time interval goes to zero.

What is the formula of acceleration ?

➜ $\sf{a = \dfrac{v - u}{t}}$

➜ $\sf{\dfrac{Change\: in\: velocity }{time}}$

➜ $\sf{a = \dfrac{v_{f} - u_{i}}{t}}$

Where,

• a is the acceleration
• v is final velocity
• u is intial velocity
• t is time taken
• $\sf v_{f}$ is final velocity
• $\sf u_{i}$ is intial velocity

What is the SI unit of acceleration ?

➜ The SI unit of acceleration is m/s².