What is the coefficient of static friction between the book and the tabletop?

LostenPhysics: What is the coefficient of static friction between the book and the tabletop?
When you push a 1.85-kg book resting on a tabletop, it takes 2.22N to start the book sliding. Once it is sliding, however, it takes only 1.54 N to keep the book moving with constant speed.

What is the coefficient of static friction between the book and the tabletop?
What is the coefficient of kinetic friction between the book and the tabletop?

Answers and Views:

Answer by Steve
µs = Fs/mg = .122

µk = Fk/mg = .085

Answer by water4145
Acceleration is 0 in both the X and Y directions for both cases (Constant velocity means acceleration is 0). To find the coefficient of friction you will first need to find the normal force. To do this use Newton’s Second Law: F = ma

F = ma(in Y direction)
(Normal Force) – (1.85)(9.81) = (1.85)(0)

Normal Force = 18.15 N

F = ma(in X direction)
(2.22) – (Coefficient of Static Friction)(18.15) = (1.85)(0)

Coefficient of Static Friction = 0.122

F = ma (in X direction again)
(1.54) – (Coefficient of Kinetic Friction)(18.15) = (1.85)(0)

Coefficient of Kinetic Friction = 0.085