Determine whether the object is floating or not

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To determine if the cylindrical object floats or sinks, the nonuniform density must be integrated to find the total mass. The density function, ρ = 6αH + 4αh, varies with height, complicating direct density comparisons. The liquid's density is given as ρliq = 9αH, which will be compared to the average density of the object. If the average density of the object is less than the liquid's density, it will float; otherwise, it will sink. Understanding the object's orientation and submerged volume requires further calculations based on the total weight and buoyant force.
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I have this homework question in fluids.
A cylindrical object has one of its flat ends painted red and the other painted green. It has a radius R and height H and has a nonuniform density given by the function ρ = 6αH + 4αh where h is the distance measured from the red end, and α is a positive number with units of density per length.
(a) Will this object float in a container of liquid of density ρliq = 9αH or will it sink? (Make an argument using math.)
(b) If it floats, what orientation will it float in stable equilibrium, and how much of the cylinder will be submerged? If it sinks what is the normal force that the base of the container exerts on the cylinder? (Either way, draw a diagram.)

Here is my answer so far: i know that to determine if the object is float or sink, we compare the density of the object and density of the liquid.
My concern is that: how can I proceed when the density of object is not constant (nonuniform)?
 
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thumn said:
I have this homework question in fluids.
A cylindrical object has one of its flat ends painted red and the other painted green. It has a radius R and height H and has a nonuniform density given by the function ρ = 6αH + 4αh where h is the distance measured from the red end, and α is a positive number with units of density per length.
(a) Will this object float in a container of liquid of density ρliq = 9αH or will it sink? (Make an argument using math.)
(b) If it floats, what orientation will it float in stable equilibrium, and how much of the cylinder will be submerged? If it sinks what is the normal force that the base of the container exerts on the cylinder? (Either way, draw a diagram.)

Here is my answer so far: i know that to determine if the object is float or sink, we compare the density of the object and density of the liquid.
My concern is that: how can I proceed when the density of object is not constant (nonuniform)?
Use integration to figure out the total weight, and the volume is fixed by the rigid container's dimensions.
 
thumn said:
I have this homework question in fluids.
A cylindrical object has one of its flat ends painted red and the other painted green. It has a radius R and height H and has a nonuniform density given by the function ρ = 6αH + 4αh where h is the distance measured from the red end, and α is a positive number with units of density per length.
(a) Will this object float in a container of liquid of density ρliq = 9αH or will it sink? (Make an argument using math.)
(b) If it floats, what orientation will it float in stable equilibrium, and how much of the cylinder will be submerged? If it sinks what is the normal force that the base of the container exerts on the cylinder? (Either way, draw a diagram.)

Here is my answer so far: i know that to determine if the object is float or sink, we compare the density of the object and density of the liquid.
My concern is that: how can I proceed when the density of object is not constant (nonuniform)?
Sooner or later, you'll need to find the mass of the object. This will make it easier to determine if it is floating than by comparing the density of the object (which is non-uniform) with the density of the fluid.
 
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The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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