How Is Friction Affecting the Motion of a Block on a Horizontal Surface?

[DeltaIceman]

Homework Statement

A 3.52 kg block located on a horizontal frictionless floor is pulled by a cord that exerts a force F=12.6N at an angle theta=31.0degrees above the horizontal. The floor has a coefficient of kinetic friction µk = 0.04, what is the magnitude of the frictional force on the block when the block is moving? There is a second part which is What is the magnitude of the acceleration of the block when friction is being considered? Although I think I am forgetting forumals or something. If someone can just send me along the right track I think I can figure it out. Thanks!

m = 3.52
F= 12.6
Theta = 31 degrees
µk = 0.04

Homework Equations

Sine and cosine functions.
µkFn= fk

The Attempt at a Solution

 

[LowlyPion]

You mean you think you are missing F = ma?

(Less of course the correction you will need to make for the retarding force of friction.)