Respuesta :

jackstattershal
The guy below is wrong!


F=ma
Where force = mass x acceleration

We dont have acceleration, a= change in velocity divided by the time taken.
a = v (final velocity) - u (initial) / t
a us 8-0 (at rest means u was 0) / 20 = 0.4

Using F=ma

F= mass x acceleration 
F= 4 x 0.4
F=1.6 N