Question

How do you calculate force normal and force friction if the object has a constant acceleration?

Answer 1

It depends on what type of platform the object is on.

Answer 2

Take the instance of an object on a flat surface.
In this case, we can express the sum of the forces in the y-direction as the following
\[\sum F_y=N-mg=0 \rightarrow N=mg\]
This means that the normal force exerted on the object by the surface is simply that objects weight!

Also, friction is always modeled as:\[F_f=\mu N\]
Where μ is the coefficient of friction.
In this scenario, since N is just mg, then our equation for frictional force is:
\[F_f=\mu mg\]