Fluids Problem help invovling floating

[xnitexlitex]

Homework Statement

A racquetball with a diameter of 5.6 cm and a mass of 42 g is cut in half to make a boat for American pennies made after 1982. The mass and volume of an American penny made after 1982 are 2.5 g and 0.36 cm3. How many pennies can be placed in the racquetball boat without sinking it? (The density of water is 1000 kg/m3.)

Homework Equations

F_B = m_objectg

The Attempt at a Solution

I've tried finding the densities of both objects and equating it to 1000 to find the number of pennies, but it didn't work. What else should I do?

 

[gneill]

What's the buoyant force on a racquetball submerged to half its diameter?