A car starts from rest , then accelerates at 1.20 m/s^2 fo 7.00 s. It hits the brakes, slowing to a stop at a rate of -4.25 m/s^2. What is the total time for the problem? (Unit = s)

8.976 seconds

Explanation:

Initial Velocity (u) = 0

Acceleration (a) = 1.20 m/s^2

Time taken (t) = 7s

Negative acceleration = -4.25 m/s^2

To calculate the total time taken :

Time taken during the first phase of movement = 7 seconds

Final Velocity attained (V) equals :

Using v = u + at

v = 0 + 1.20(7)

v = 0 + 8.4

v = 8.4m/s

Therefore, time taken to bring the car to a stop.

Here final Velocity (v) = 0 ;

Initial Velocity (u) = 8.4m/s

From v = u + at

0 = 8.4 + (-4.25)t

0 = 8.4 - 4.25t

4.25t = 8.4

t = 8.4 / 4.25

t = 1.976 seconds

Therefore, total time taken equals:

7s + 1.976s = 8.976seconds