# Homework Help: Buoyant force problem

1. Dec 10, 2006

### mikefitz

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

Buoyant force. A block of wood floats in
oil with 90.0% of its volume submerged. What
is the density of oil? The density of the block
of wood is 0.67 g/cm3.

2. Relevant equations

buoyant force = pgV

3. The attempt at a solution

p(oil) V(oil)=p(h20) V(h20)

p(oil)= p(h20) V(h20) / V(oil)

i know that the V(oil) displaced is equal to .9V(h20)

so, p(oil) = .67 V(h20) / .9 V(h20)

do the terms 'V9h20' simply cancel, leaving me with .67/.9? Thanks

2. Dec 10, 2006

### billiards

h20? hmmm where did you get that from,I hope you dont mean H2O because my friend this problem has no water to be seen!

You need to use the fact that the block is in equilibrium, thus the buoyancy force is equal and opposite to another force.... hmmmm what could that be. It's really easy, have another go at a solution.

3. Dec 10, 2006

### mikefitz

gah i was half working on another problem while typing this one out, sorry for the stupid typo; thanks for the response