Ff = friction force , net force = F, a = acceleration , speed= v
If u have an object thate is moved by a force F on X axis , will be a friction force oposite to the F.
F=ma (m=mass)
miu= frection coefficient
N= normal at surface
Ff=(miu)N
Billance of forces on oX-axe is :
F-Ff = ma - (miu)N
if the v = constant , a=0