3. how long does it take an object to decrease its
velocity from 64.0 m/s to 26.8 m/s if the acceleration
is -5.38 m/s? ?
how to solve for

t = 6.91 s

Explanation:

Given,

The initial velocity of the object, u = 64.0 m/s

The final velocity of the object, v = 26.8 m/s

The acceleration of the object, a = -5.38 m/s²

The formula for acceleration of the body is given by the relation

                                a = (v - u) /t     m/s²    

Solving for time

                                t = (v - u) / a      s

Substituting the values in the in the above equation

                                t = (26.8 - 64) / -5.38

                                  = 6.91 s

Hence, the time taken by the body is, t = 6.91 s

i'm thinking more like energy