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

Answer:

The answer to your question is: t = 2.5 s

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

Answer:

2.5 s.

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.

$0=30+(-12)t\\t=\frac{30}{12}\\t=2.5 s$

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