# Homework Help: Static friction and kinetic friction

1. Sep 10, 2006

### Revolver

Another concept my physics prof didn't teach the class. I would love to be able to attempt these problems but I have no idea what these concepts are or the formulas for them. I'm not looking for the answers to these problems here folks, but rather a method in which to solve them. Thanks!

1. A 750 N box moves at a constant velocity on a floor with a coeficient of static friciton of .800 and a coefficient of kinetic friction = .600. What is the horizontal force required to keep the box moving?

All I can think to do here is draw a diagram with vectors, but I honestly have no idea what to do.

2. A 750 N box rests on hte floor with a coefficient of static friction = .800 and a coefficient kinetic friciton of 0.600. What is the force of friction if a horizontal force of 550 N is applied to the box?

Again, no idea.

3. In order to slide a 70.0 kg box across the floor at a constant speed, you must push horizontally with a force of 351 N. What is teh coefficient of kinetic friciton?

Last edited: Sep 10, 2006
2. Sep 10, 2006

### Staff: Mentor

Drawing a diagram would be a good start...

3. Sep 10, 2006

### Revolver

I did.. thing is I don't know the formulas, or the method to solve it. I'm not looking for the answer, but rather for someone to explain how to tackle these problems. Thanks.

4. Sep 11, 2006

### Revolver

Anybody know the formula?

5. Sep 11, 2006

### Hootenanny

Staff Emeritus
Last edited by a moderator: Apr 22, 2017
6. Sep 11, 2006

### hakojackie

The formula you want is Fmax=Us*Fn where Fs is what you are trying to find and Us (meu) is the coefficient of static friction and Fn is normal force