Calculating Coefficient of Kinetic Friction: Object Sliding on a Level Surface

[Ryfull10]

Homework Statement

An object slides on a level surface in the positive x direction. It slows and comes to a stop with a constant acceleration of -2.45 m/s/s. What is the coefficient of kinetic friction between the object and the floor?

Homework Equations

a = F/m

The Attempt at a Solution

I have been sitting at my desk for about 15 minutes and am still scratching my head. I also don't even know what a "coefficient of friction" is, my teacher just told us that it is mu. What does it mean/represent?

However, I tried using a = F/m but don't know where to go from here...is that the right start? Thanks in advance

 

[Ryfull10]

Wait wait so it would be -2.45 = F / m

F = mgu

-2.45 = mgu/m

-2.45 = 9.8(u)

u = -0.25.

Is the correct process?

 

[jmb88korean]

I believe the above work is correct ecept that I don't believe its possible to have a negative coeffient of friction. Since friction itself is a retarding force, its inherently negative, thus it would look like (-2.45m)= -F thus the acceleration become positive.

 

[flyingpig]

I believe the above work is correct ecept that I don't believe its possible to have a negative coeffient of friction. Since friction itself is a retarding force, its inherently negative, thus it would look like (-2.45m)= -F thus the acceleration become positive.

Yeah, but here is the more correct way

T - Ffrc = ma

But nothing is pulling it so T = 0

0 - Ffric = ma

Since a is negative we have

-Ffric = m(-a)