a car slows down uniformly from a speed of 21.0 m/s to rest in 6.00 s. how far did it travel in that time?

The keyword slows down “uniformly” means that the car had a constant deceleration. Therefore we can use the formulas for linear motion.

a = (vf – vi) / t                    ---> 1

s = vi t + 0.5 a t^2              ---> 2

where a is acceleration, v is velocity with notation f and i for final and initial, s is the distance travelled, and t stands for time

First we solve for acceleration using equation 1:

a = (0 – 21) / 6

a = - 3.5 m / s^2                                (negative means deceleration)

Then we can now calculate for the value of s using equation 2:

s = 21 (6) + 0.5 (-3.5) (6)^2

s = 63 m

Therefore the car travelled 63 m before it came to a stop.

the total distance traveled by the car is

30km + 49km = 79 km .