I am not a student, but once took physics in college more that 20 years ago.(adsbygoogle = window.adsbygoogle || []).push({});

I have the following problem that I am having trouble with:

A book has a mass of 400 grams. When you slide the book against the floor with a force of 5 N, it accelerated at a rate of -1.5 m/s^2.

What would the coefficient of friction be between the book and the floor?

So, my solution seems to be:

Where F is force

N is normal force

FF is force of friction

u is coefficient of friction

I know F = ma, N = -mg, and FF = uN, so that FF = -umg.

Is this just a matter of setting ma = -umg, then a = -ug, and then u = -a/g ?

So given that g = 9.8 m/s^2:

I get an answer of 0.15, is this correct?

Is this the correct way to approach this problem?

Is the 5 N force just unneeded information here?

Thank you for your help

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Find coefficient of friction

**Physics Forums | Science Articles, Homework Help, Discussion**