How to find the coefficient of friction?

[trASHf]

Homework Statement

Unknown object has a mass of 3.2kg on steel plank.

Add force:
|FA|=22.8N
|a|=3.02m/s^2

What is the material?

Relevant Equations

Newton's Second Law - sum of all forces = mass * acceleration = ...

GR (bold = mathematical convention)
m = 3.2kg
|applied force| = + 22.8 N
|acceleration| = + 3.02 m/s^2

FBD-hypothetical
^ normal force
|
friction force <-----*-----------> applied force
|
gravitational force

A
ma = FA + FfK
ma = FA -Mmg
ma/mg = FA - M
ma/mg - FA = -M

 

[BvU]

Hi,

Can you imagine it is hard to make sense of this ? Read what you posted

 

[trASHf]

Hi,

Can you imagine it is hard to make sense of this ? Read what you posted

other than the attempted solution I put there, no I don't think it's hard to make sense of this.

 

[kuruman]

ma = FA + FfK
ma = FA -Mmg
ma/mg = FA - M
ma/mg - FA = -M

Your algebra is faulty when you go from the second equation to the third. You need to divide all the terms on the right side by mg.