a lead cannonball and?

Question

a ordinary golf ball ,dropped exactly at the same time from a height of say 50ft ,will both reach the ground together,even though one is far heavier and bigger than the other~ok

my Q is- if 2 bouyant objects one far larger than the other
were taken down say 100ft under the sea or lake etc,and released both exactly at the same time,would they both travel
at the same speed upwards together or would weight and size of each object,have an effect on their individual ascending speed

both bouyant objects contain air

Answer 1

I think their weights would come into play. Because with buoyancy the objects are fighting gravity, the more mass a thing has the more gravity affects it.

If one was larger, but they had the same mass, and same amount of buoyancy then they'd probably raise at the same time.

Answer 2

The thing to concentrate on is the viscosity of the thing the things are moving through.Air would not make much difference to the time taken for a leadball or golf ball to fall 50ft assuming both are the same size and shape.But if the same objects were to fall or rise through treacle,water,engine oil,olive oil(to give a small choice for home investigation)you wouldnt need a stopwath to see that viscosity is important.There are lots of books of not very highflying mechanics which deal with the subject.
Given two object of the same mass and density, but one a ball the othe tear shaped,The tear shape would move faster.

Answer 3

No, unlike in air it's not the weight of the object which is important. The upward force acting on the buoyant object depends on the weight of water which it displaces. Therefore, assuming that both objects have the same weight in air, then the larger object will rise faster.

Answer 4

The size and shape of the objects IS important. The larger object in air will "catch" more air, and slow down. This is called aerodynamics. A larger object will "catch" more water when floating, and also slow down. This is called fluid dynamics.

Answer 5

Your example of the dropped ball neglects to figure in air resistance, which is OK because it is negligible.
In the much denser medium of water, while the force on the object would be in proportion to its volume, (a cube function), the resistance to its rise, (a square function), would not.

Answer 6

if there is no air in any of the objects, or the object is heavier than the weight of the same sized water-ball, they will sink

Answer 7

The larger object will reach first because it can hold more air and will hence have more "lift"