How far a cube sinks below the waterlevel

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The discussion revolves around a physics problem involving a wood cube with a density of 700 kg/m^3 floating in water. For part (a), the user successfully calculates the distance from the top of the cube to the water surface but struggles with part (b), which requires determining the mass needed to make the cube's top level with the water. The user attempts to apply the buoyancy equation but arrives at an incorrect mass of 27 kg, while the solution in the textbook states 8.9 kg. Additionally, the user inquires about the weight of a cube of water with the same dimensions, indicating confusion about the calculations. The thread highlights common challenges in understanding buoyancy and density in physics problems.
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Homework Statement


A wood cube .30m on each side has a density of 700 kg/m^3 and floats levelly in water. (a) What is the distance from the top of the wood to the water surface? (b) What mass has to be placed on top of the wood so that its top is just at the water level.


Homework Equations


I assume the buoyancy equation.


The Attempt at a Solution


I figured out part (a) no problem, but seem to be having difficulty with part (b).

I assume it has to be:
Density=(mass/volume)?
When i do that I get 18.9, where the back of the book says 8.9

Thanks guys so much! Hope once I actually get good at physics I can come back and help people similar to myself!
 
Physics news on Phys.org
How much would the wooden block weigh if its density was the same as the density of water?
 
Sorry, but I'm still lost?

So

1000=(mass/.027)
mass=27?

Thanks!
 
27 what?
 
27kg

Which is not what they had in the back of the book (they had 8.9).

Thanks You again!
 
How much does a cube of water weigh which is 0.30 m on each side?
 

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