# Beach ball physics buoyancy

1. Mar 28, 2014

### whattheheckV

A beach ball is made of thin plastic. It has been inflated with air, but the plastic is not stretched. By swimming with fins on, you manage to take the ball from the surface of a pool to the bottom. Once the ball is completely submerged, what happens to the buoyant force exerted on the beach ball as you take it deeper?

Now I know that Archimedes' principal states that the buoyant force is equal to the weight of the displaced water. This is a multiple choice question and I choose that the buoyant force remains the same, and it said i was wrong. All help appreciated.

2. Mar 28, 2014

### Staff: Mentor

Hi whattheheckV. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

Pearl divers found that the deeper they went, the greater the pressure.

Last edited by a moderator: May 6, 2017
3. Mar 28, 2014

### cheah10

I'll give you a tip: gas is compressible.

Last edited: Mar 28, 2014
4. Mar 28, 2014

### Staff: Mentor

Hi WhattheheckV. Welcome to Physics Forums!!!

If a submarine goes too deep, its hull gets crushed. As you go deeper with the beach ball, its surface starts to wrinkle and buckle, and, as a result, its volume decreases. (If the beach ball were rigid, its volume wouldn't change, the buoyant force would remain constant).

Chet