A force of 150 N accelerates a 25 kg wooden chair across a wood floor at 4.3 m/s2. How big is the frictional force on the block? What is the coefficient of friction between the chair and floor?

We can first calculate the net force using the given information.

By Newton's second law, F (net) = ma:

F (net) = 25 * 4.3 = 107.5

We can now calculate the frictional force, f, which is working against the applied force, F (app) (this is why the net force is a bit lower):

f = F (net) - F (app) = 150 - 107.5 = 42.5 N

Now we can calculate the coefficient of friction, u, using the normal force, F (N):

f = uF (n) - - > u = f/F (N)

u = 42.5/[25 (9.8) ]

u = 0.17