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Hi, I'm having some difficulty understanding what the relationship between density and buoyancy is. If you can help explain it to me, then that would be greatly appreciated. Thanks.

It's easier than you're making it, in all likelihood.  Density is the amount of mass per unit volume of an object or substance.  Buoyancy is the force exerted on an object immersed in it by the liquid it displaces, always equal to the weight (mg) of the fluid displaced.  The mass m of the fluid displaces is equal to its density multiplied by its volume.  The volume displaced is the same as the volume of the object, an its mass is equal to volume*density for the object.  The weight of the object is always there, but the buoyant force is there as well, pushing upwards on the object.  Again, always equal to the weight of the fluid displaced as specified above.


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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