SpudFiles

i know this isn't a cannon, but was wondering if this would work, would a pressurized buoy ( probably just a 4" pvc pipe with two endcaps) at 100psi have more buoyancy than with out the pressure?

im thinking of making a topwater ROV and was wondering if this could compensate for the weight of all the gear

edit by MrC: Not exactly sure what this had to do with combustions, it's like you just randomly selected a topic section without reading, or thinking for that matter. Topic moved.

Internal pressure has nothing to do with buoyancy. Buoyancy is determined by weight and displacement.

ok so it wouldn't affect how much it would float at all? thanks

If you put more pressure in it, it will be less boyant because of the extra ( minimal) weight of the air..

A vacuume would create slightly better boyancy..not noticable but still..

ok thanks for the feed back

That said, if you plan on taking it super duper deep, having some internal pressure in the pipe to counteract the immense pressure from the water might not be a bad idea...

Bouyancy = weight of the water displaced by the object - weight of the object.

Any part of the object that is out of the water contributes to the weight but not to the volume of displaced water.

Air at 1 ATM weights about 1g per liter. 1 liter of water weighs 1000 grams. You chamber probably weighs a couple hundred grams. So the gas inside the chamber contributes relatively little to the total weight of the chamber. If you used air at 2 ATM you would increase the total weight, and decrease the bouyancy, by 1 gram. (Roughly the weight of 20 drops of water.)

If you pumped the chamber down to a full vacuum the bouy would be able to lift (bouy) about 1 more gram than with air at 1 ATM.

jimmy101 wrote:Air at 1 ATM weights about 1g per liter.

WRONG. It's 1g per mililiter.

Gun Freak wrote:

jimmy101 wrote:Air at 1 ATM weights about 1g per liter.

WRONG. It's 1g per mililiter.

Pure water weighs 1 gram per milliliter...last time I checked...air was lighter than water.

He's a heck of a lot closer than you are. If I decide to trust wikipedia ( ), I get 1.2grams per liter.

http://en.wikipedia.org/wiki/Density_of_air

Oh crap, I thought he said water