calculating buoyancy?

Question

How do you calculate your buoyancy in sea water if you weigh 40kgs and the density of sea water is 1020kg

Answer 1

That's not enough information--buoyancy depends on the volume of the thing being submerged. (For example: 40 kg packed into a small lead cube would be much less buoyant than 40 kg spread out in the form of, say, a big wooden log).

Also, I think you meant to say "1020 kg per liter" for the density of sea water; not "1020 kg".

If you know your own density, you can figure out your volume by dividing 40kg by your density. Or you can figure out your volume by submerging in a bathtub and measuring how much water you displace. Then you can figure out the force of buoyancy acting on you. It would be:

[your (submerged) volume] x [density of sea water]

You will float if your density is less than that of the sea water.

Answer 2

First I gonna calculate my body volume. I can use bath tube.
I will make volume mark on the bath tube for each 5 liter water I add tu the bath tube, until the bath tube is fully loaded.
Than slowly, I gonna enter to the bath tube until all my body is under the water surface.
Than still slowly, I gonna out from that bath tube.
From here I know my volume in m3 is (V).
Because my weight is 40 kgs, all I need to know is the weight of sea water in my body volume = V x 1020 = Buoyancy

While, my reserve of buoyancy is = Buoyancy - My weight.

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Answer 3

If V is volume of water displaced,

(1020 xV) x g is the buoyant force that acts up.