cork capacity of elevation

Question

Hello,

I have an in water floating plastic-ABS bowl , surface 40 x 16 cm, in total 6 kg,

if I put 84 gr. of Cork, density 0.4 gr/cm³ , under it,

how much cm. will it rise in the water ?

84 gr./ 0.4 gr.-cm³ = 210 cm³ volume cork

40 cm x 16 cm = 640 cm² / 210 cm³ cork = 3.048 cm elevation ???

Is my thinking correct ?

Greetings,

Danny

Answer 1

Hi Danny D.

Not the right information to answer that question. The bouyant force of the cork will be the mass of the displaced water minus the mass of the cork, so that will be (approximately) 210 g - 84g = 126 g worth (I know, that's not a force unit). But, how far that bumps the ABS bowl up, depends on the shape of the bowl, which you haven't stated. If the bowl were truly a rectangular prism, with bottom 40 x 16 cm, and vertical sides, then you can use the bottom area of 640 cm^2 to calculate a rise of 126/640 or about 0.2 cm. In other words, if the bowl raised by that amount, it would be displacing that much less mass of water, to balance all the forces.

I that's not enough rise for the intended use, perhaps you need to employ "cork-rective measures"?

-- Cheers, -- Mr. d.