Answered By Vishesh M

from the problem we see

initial velocity(u)= 0;

final velocity(v)=1.25m/s;

therefore from the formula v = u + at;

we find accelaration

i.e

1.25 = 0 + a(3);

a=0.4166m²/s;

we know that F = m*a;

F = 12*0.4166;

F= 5 N;

however this is the normal force.

frictional force

F_{f =} F_{n/0.81(frictional coefficient)}

F_{F=5/0.81= 6.17 N;}

therefore you need a force of 6.17 newtons.