Acar's brakes decelerate it at a rate of -2.10 m/s2. What is the time, in seconds, required to slow the car from 13 m/s to 5.0 m/s?

t = 3.8 [s]

Explanation:

To solve this problem we must use the following equation of kinematics.

where:

Vf = final velocity = 5 [m/s]

Vo = initial velocity = 13 [m/s]

a = desacceleration = 2.1 [m/s²]

t = time [s]

As we can see in the above equation the acceleration is negative because the car slows down its velocity.

5 = 13 - 2.1*t

2.1*t = 13 - 5

t = (8)/2.1

t = 3.8 [s]

the area between the graph and the t axis