Finding acceleration of an object on a horizontal surface

[Sunchild16]

Homework Statement

The coefficients of static and kinetic friction between a 59 kg box and a horizontal surface are 0.66 and 0.37, respectively.

(a) What is the acceleration of the object if a 330 N horizontal force is applied to the box?

(b) What is the acceleration if the applied force is 485 N

Homework Equations

F=ma, coefficient of friction equations

The Attempt at a Solution

I tried using the equations

but I am not really sure how they are supposed to be used

 

[renaldocoetz]

Is this applied to the box at rest? in that case the applied force has to be greater than the max Static Friction for the box to have any acceleration.