car starts from rest
[tex]v_i = 0[/tex]
final speed attained by the car is
[tex]v_f = 5 m/s[/tex]
acceleration of the car will be
[tex]a = 3.6 m/s^2[/tex]
now the time to reach this final speed will be
[tex]t = \frac{v_f - v_i}{a}[/tex]
[tex]t = \frac{5 - 0}{3.6}[/tex]
[tex]t = 1.39 s[/tex]
so it required 1.39 s to reach this final speed