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!