Question

a car acquires a velocity of 72km/hr in 10 seconds starting from rest. Find (i) acceleration
(ii) distance travelled​

Answer 1

Given :

• A car acquires a velocity of 72km/hr in 10 seconds starting from rest.

To find :

(i) Acceleration

(ii) Distance travelled

Solution :

we have,

⟶ Initial velocity of the car = 0 m/s [Because it started from rest.]

⟶ Final velocity of the car = 72 km/h

⟶ Time = 10 seconds

Firstly, we shall convert the final velocity of the car from km/h into m/s.

★ To convert the final velocity from km/h into m/s mulitply it by 5/18.

⟶ Final velocity = 72 × 5/18

⟶ Final velocity = 4 × 5

⟶ Final velocity = 20

Therefore, the final velocity of the car = 20 m/s

Now, by using the first equation of motion we will find the acceleration of the car.

First equation of motion :-

• v = u + at

where,

• v denotes the final velocity

• u denotes the initial velocity

• a dneotes the acceleration

• t denotes the time

Substituting the given values :-

⟶ 20 = 0 + a(10)

⟶ 20 = a × 10

⟶ 20/10 = a

⟶ 2 = a

Therefore, the acceleration of the car = 2 m/s²

Now, by using the third equation of motion we shall find the distance travelled by the car.

Third equation of motion :-

• v² - u² = 2as

where,

• s denotes the distance/displacement

Substituting the given values :-

⟶ (20)² - (0)² = 2(2)(s)

⟶ 400 = 4 × s

⟶ 400/4 = s

⟶ 100 = s

Therefore, the distance travelled by the car = 100 m