# Buoyancy .check me

1. Nov 18, 2007

### gills

buoyancy.....check me

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

2. Relevant equations

$$\rho$$ = $$\frac{m}{V}$$

F(buoyancy) = $$\rho$$liquid * Vsolid * g

3. The attempt at a solution

I think i got this, i just want someone to check my answers if you can...

$$\rho$$_gold = 19.3 g/cm$$^{3}$$ = 19300kg/m$$^{3}$$
$$\rho$$_silver = 10.5 g/cm$$^{3}$$ = 10500kg/m$$^{3}$$
$$\rho$$_water = 1000kg/m$$^{3}$$

(a)
W = 25N = mg --> m = 2.55kg

W_u/w = W - Fb ---> mg - $$\rho$$_water * $$\frac{m}{\rho_gold}$$ * g

W_u/w = 23.71 N

seem right?

2. Nov 18, 2007

### dynamicsolo

Looks OK so far...

3. Nov 18, 2007

### gills

ok, that's all i needed. The next part i multiply the density of gold by 0.75 and silver by 0.25 and add them together. I then use that as the denisty of the solid. And the weight comes out to 23.54 N. Not that much lighter.

4. Nov 18, 2007

### dynamicsolo

That looks fine, too.

5. Nov 18, 2007

thank you!