Answer:
The car will reach 20 m/s in 4.76 seconds
Explanation:
The car moves following an uniformly accelerated motion, therefore we know that [tex]v=v_0+ a(t-t_0)[/tex]
Where [tex]v_0 = 0[/tex] are [tex]t_0 =0[/tex]
Then [tex]t= \frac{v}{a}=\frac{20 m/s}{4.2 m/s^{2}}=4.76s[/tex]