Question

How large a force is required to accelerate a 1300-kg car from rest to speed of 20m/s in a distance of 80m ?

Answer 1

The energy-work theorem says

$$\frac{mv^2}{2}=Fd$$

Hence, the required force

$$F=\frac{mv^2}{2d}=\frac{1300*20^2}{2*80}=3250\:\rm N$$