# Static and kinetic friction

1. Oct 20, 2011

### universitybou

1. The problem statement, all variables and given/known data

When you push a 1.55 kg book resting on a tabletop it takes 2.50 N to start the book sliding. Once it is sliding, however, it takes only 1.50 N to keep the book moving with constant speed. What are the coefficients of static and kinetic friction between the book and the tabletop?

2. Relevant equations

Force of static/kinetic friction= "mu" (looks like a u with a tail in the front) * normal force

3. The attempt at a solution

2. Oct 20, 2011

### Delphi51

Welcome to PF!
Look at the bottom of my post; you'll see "μ" and some other symbols you can copy and paste into a post. There are more of them here:
https://www.physicsforums.com/blog.php?b=346 [Broken]

I can't help you much until you attempt the problem. Can you at least write out the formula for friction force? It will have the μ in it, so solve for that. See if you can calculate the other unknowns in the formula. Let us know what trouble you have and we'll be glad to help.

Last edited by a moderator: May 5, 2017