Hallo Shereen,
$$F = m ·a → a = \frac{F}{m}=\frac{1200 kg}{3800 N}≈0,316\frac{m}{s^2}$$$$100 \frac{km}{h}≈27,8\frac{m}{s} $$$$a=\frac{Δv}{Δt}→ \color{blue}{Δt=} \frac{Δv} {a} = \frac {27,8\text{ } \frac{m}{s} } {0,316 \text{ }\frac{m}{s^2} }\color{blue}{≈88,0\text{ }s}$$Gruß Wolfgang