Re: How much will it float (55 gal plastic barrel)?
that's inherent in the calculation. If I have a drum, and put it into water, the force acting up on the drum is equal to the weight of the water. If the drum is filled with air, and hence lighter than water, it will float, if it's filled with concrete and heavier than water, the water is still pushing up with the same force, but it can't overcome the weight of it
here's one for you, a bowling ball has a certain weight, when placed in a canoe, it floats, but when placed into the water it sinks, why?
If you vaccum the drum completely, the drum will weight less and thus provide greater bouyancy.
WRONG !! If the plastic drum is filled with a complete vacuum, atmospheric pressure will colapse the drum and it's only bouyancy will be the difference in the weight of the plastic and the weight of the water it displaces. Kinda like trying to float on an uninflated balloon or empty air mattress.
EDIT: Atmospheric pressure at sea level is 14.7 lb/sq.in or nearly 1 ton per sq. ft. (11sq.ft = 10.3 tons)
Well it's about this displacement of water that leads to the buoyancy force. Anyway, the reasoning behind the styrofoam is that it will support and reinforce the plastic drum. Even if the drum gets dented, scuffed, a cut in it etc if full of styrofoam it will be essentially undamaged. (In it's role as the dock float)
If you vaccum the drum completely, the drum will weight less and thus provide greater bouyancy.
WRONG !! If the plastic drum is filled with a complete vacuum, atmospheric pressure will colapse the drum and it's only bouyancy will be the difference in the weight of the plastic and the weight of the water it displaces. Kinda like trying to float on an uninflated balloon or empty air mattress.
EDIT: Atmospheric pressure at sea level is 14.7 lb/sq.in or nearly 1 ton per sq. ft. (11sq.ft = 10.3 tons)
I'm glad someone responded to this and explained it. I knew it was wrong, but couldn't explain why.