# Physics question about items sinking in water

1. Oct 21, 2005

### r3dxP

A tin cup has a total volume of .012m^3 and mass of .13kg. How many grams of lead shot of density 11.4g/cm^3 could it carry without sinking in water?

the question i have here is what is equal to what and how to solve this?
so far.. i have.. Ftin = Vpg = .012m^3 * 7310kg/m^3 * 9.8m/s^2 = 860N
the tin alone pushes down 860N onto the water.
how can i find the force pushed by the water in the sink? cause once i find this force, i can set the equation.. Ftin + Flead = Fwater
once i get the Flead, i can solve for mass by Flead / g..

2. Oct 21, 2005

### Diane_

And Archimedes' Principle rears its attractive head for the second time in twenty-four hours.

The buoyant force will equal the weight of the water displaced by the cup.

3. Oct 21, 2005

### r3dxP

how can i solve for the buoyant force?

4. Oct 21, 2005

### Diane_

You know the total volume of the cup - you therefore know the maximum amount of water it can displace, yes? Just find the weight of that much water and Bob's your uncle.

Clear?