Question

A car is travelling at a speed of 30 m/s. It decelerates at a rate of 12 m/s^2. Calculate the time taken for the car to come to a rest.

Answer 1

The answer to your question is: t = 2.5 s

Step-by-step explanation:

Data

vo = 30 m/s

a = -12 m/s2

t = ?

vf = 0 m/s

Formula

vf = vo + at

Substitution

0 m/s = 30 + (-12)t

Solve it for t -30 = -12t

t = -30 / -12

t = 30/12 = 15/6 = 5/2

t = 2.5 s

Answer 2

2.5 s.

Step-by-step explanation:

The car is travelling initially with a speed of ,
`u=30m/s`

And the deacceleration of the car is,
`a=-12m/s^(2)`

The car comes to rest so, final velocity will be zero.

From the first equation of motion.

`v=u+at`

Here, u is the initial velocity, v is the final velocity, a is the acceleration and t is the time taken.

Put all the variables from above.

`0=30+(-12)t\\t=(30)/(12)\\t=2.5 s`

Therefore, the time taken by the car comes to rest is 2.5 s.