# Homework Help: Coefficient of Friction (Styrofoam on Water)

1. Nov 20, 2007

### dashed

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

fgrav = mg
fgrav = (0.0821)(9.8) = 0.80458 N

fnet = ma = (0.0821)(0.0096) = 0.0096 m/s^2

fnorm = fgrav

2. Relevant equations

kinetic mew = force of friction / fnorm

3. The attempt at a solution

Required: Ffr

kinetic mew = force of friction / fnorm
kinetic mew = force of friction / 0.80458 N

I need to find the friction of the object when it is on the water. The object is made out of styrofoam. I'm completely stumped and I tried looking around internet using the google search engine to find the coefficient of friction of two surfaces.

2. Nov 20, 2007

### Galileo's Ghost

This does not make much sense...mathematically, it is not true. (0.0821)(0.0096) = 0.00079.

Also...what forces are acting on this styrofoam contributing to fnet? is friction the only force and the styrofoam is actually slowing down? Or are there other forces involved?

If it is the first case, then 0.00079 = force of friction and "mu" can be calculated as per the equation you show. If it is the second case, the force of friction can be calculated using the fnet equation and the values of the other forces involved.

3. Nov 20, 2007

### dashed

there is Fa which is opposite of Ffr. However at the moment Fa is unknown.