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HadManySons
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Homework Statement
The first part of the question states this: If we want to buoy a 0.137 kg solid platinum object in water with an attached string from above, what is the tension required to support the piece of platinum?
The correct answer is: 1.28 Newtons. I got this by subtracting the buoyant force, which was
(.137kg/(21450kg/m^3)) * (9.8m/s^2) * (1000 kg/m^3) = .062593N
the volume of platinum g density of water
from the weight of the platinum: 1.3426 Newtons
What I'm trying to find now is this, "If the object is now attached to a piece of Styrofoam, what volume of Styrofoam (density rho_s = 95 kg/m3) should be used to have the Styrofoam and the metal floating just under the water surface?". But I've hit a stopping point and can't seem to get the right answer
Homework Equations
density = mass/volume
buoyant force = volume displaced * gravity * density of fluid
The Attempt at a Solution
I had set everything in equilibrium, meaning:
Buoyant force + Weight of Styrofoam + weight of the platinum = 0
But how do I know the volume of the water displaced if I don't already know the volume of Styrofoam that I need?