Question

A car accelerates at 3 m/s*2. Assuming the car starts from rest, how much time does it need to

accelerate to a speed of 12 m/s?

3 sec
2 sec
4 sec
12 sec
None of the other answers

Answer 1

We are given with some parameters used in Kinematics for determining the motion of an object.

• Accleration = 3 m/s²
• Started from rest (Initial vel.) = 0 m/s
• Final velocity = 12 m/s

We have to find the time taken by the car to attain the final velocity with the given accleration. By using 1st equation of motion which says:

• v = u + at

Final velocity = Initial velocity + Accl. × Time taken

Plugging the values,

➝ 12 = 0 + 3(t)

➝ 3t = 12

➝ t = 4 s

So, the correct answer is Option C. And we are done...

Carry On Learning
`!`

Answer 2

Given:-

Acceleration,a = 3 m/s²

Initial velocity,u = 0 m/s

Final velocity,v = 12 m/s

To be calculated:-

Calculate the time take by a car.

Solution:-

According to the first equation of motion:

v = u + at

★ Substituting the values in the above formula,we get:

⇒ 12 = 0 + 3 × t

⇒ 12 = 3t

⇒ 3t = 12

⇒ t = 12/3

⇒ t = 4 sec