Question

One cm of a 10-cm-long rod is made of metal, and the rest is wood. The metal has a density of 5000kg/m^3 and the wood has a density of 500kg/m^3. When the rod is set into pure water, the metal part points downward. How much of the rod is underwater?

Answer 1

well, you know the metal will all be underwater. So the question is how much wood is under to support the weight of the metal.

bouyancy of wood= h*density water*area*g

that has to equal the weight of the entire rod.

h*densitywater(area)g-.1*densitymetal*g(area -h*denstiywood*area*g=0

dividing out area, g; divideing by density water.

h-.1spgrmetal-hspgrwood=0

h= (.1 spgrmetal)/(1+sprgwood)= about .5/(1.5)=33cm ?

check my work.