# Homework Help: Help on Fluids

1. Dec 8, 2004

### monkeyman44

I have a question regarding fluids

A small sculpture made of gold (density of gold = 19280 kg/m^3) is believed to have a secret central cavity. The weight of the sculpture in air is 25.76 N. When submerged in water, the weight is 23.86 N. What is the volume of the secret cavity. (Density of water = 1000 kg/m^3)

The answer is supposed to be volume = 5.7x(10^-5). I can't seem to get that answer. I believe my approach to the problem is wrong.

this is my approach but it is wrong

F=mg

25.76 N = m(9.8 m/s^2)
m = 2.6 kg

density = mass/volume

19280 kg/m^3 = 2.6 kg / v
v = 1.3 x 10^-4

i dont know what to do with the next part after... thanks

2. Dec 9, 2004

### Staff: Mentor

This correct.

This is the volume the sculpture would have if it were solid gold--with no cavity.

What is the buoyant force on the sculpture? (You can figure it out from the information given.) Use the buoyant force to calculate the actual volume of the sculpture. Then you can figure out the size of the cavity.