# Relationship between gravity and density

So I have recently found that flat earthers believe gravity is not real and everything goes down because of densities, obviously, if this were true things would float up as our air is not very dense, but ill move on. These are a few questions I have that I cant find online because everywhere I look is talking about specific gravity which say wether or not somehting floats is completely based on density.

Is the reason an anvil floats on mercury purely due to it being so much less dense?

How does gravity affect this and what role does it play?

If we use the flat earths idea that it is only about dnesity then would the entire anvil sit ontop?

Why is a large portion of the anvil underwater?

Even if something is only, say, 0.01% less dense would it float?

I know theres a lot of qustions but this seemingly simple topic has me quite cofused. Maybe im overthinking it. If someone could explain the math and physics behind this, maybe even a force diagram of some kind to help me visualize it, to help me understand this I would really appreciate it!

• Aeon, specific gravity for liquids and solids is normally defined as the weight of an object divided by the weight of an equal volume of water. To get the density of the object in question, multiply the object's specific gravity by $1000 kg/m^3$. Mar 10, 2021 at 18:25
• @PM2Ring You are right Mar 10, 2021 at 19:41