Friction force and coefficent of friction

[zelda1850]

Homework Statement

caculate the force of friction and coefficient of fricition acting on a sliding block given that the acceleration at 3.0 m/s sqaure

Homework Equations

coefficient of friction = fn/ff
force of friction = u fn = u fg

The Attempt at a Solution

im stuck I am only given the accelaration and mass is 4 kg too how can i solve this?

 

[kuruman]

The only force in the horizontal direction is the force of kinetic friction. Use Newton's Second Law to find it.