What Is the Coefficient of Kinetic Friction for a Box Pushed at Constant Speed?

[Demonsthenes]

Okay, here's the question:

A box full of physics books (31 kg) is pushed across the floor at a constant speed by a force of F = 85 N at an angle theta = -40 degrees. Determine the coefficient of kinetic friction between the box and floor.

My question is (for later calculation) if the box is moving at constant speed, does the F = 85N really matter?

 

[russ_watters]

Absolutely - that force (the horizontal component...) is what opposes the friction to keep the speed constant.

 

[Doc Al]

That force also affects the normal force, which you'll need to figure out to calculate the coefficient of kinetic friction.