# Gravity and objects in substances

This is probably a matter of terminology and me not finding it due to the lack of it.

An apple falls from a tree on the ground due to gravity. Yet, if it falls into a water pit it floats on top of the water and doesn't sink.

I've heard about density and why it makes things float but I'm not sure why it floats to the top and does not sink to the bottom if there's still gravity. Thinking about this I could imagine the apple being pulled to the bottom just as well. Why is the play between high and low density objects not reversed?

It's all about buoyancy force that is explained in Archimedes theorem. Here is a link where you can find the full explanation wiki link buoyancy force.

It's all about this formula: Fb = ρgV = ρghA With ρ = density of the liquid(kg/m3)

g = gravitational acceleration(9.80 m/s2)

V = volume of liquid displaced (m3 or liters, where 1 m3 = 1000 L)

h = height of water displaced by a floating object(m)

A = surface area of a floating object(m2) Found on this website formulas

• oh, I missed the role of "pressure at the bottom" mentioned in the article. Yes, that makes sense. Thank you for the link. Perfectly answers my question. Commented Oct 17, 2018 at 8:14
• You're welcome :) Commented Oct 17, 2018 at 8:15