# Buoyancy Problem - Cubes in water

I have a tank with water (10 m high) , with an ideal seal at the bottom (water can't fall down, but can enter bodies).

I have a system of 6 cubes ( of polystyrene density= 20 Kg/m^3) with dimension 1x1x1 m. These cubes are connected with a rope (volume negligible). They are in vertical column, and are all submerged except one, that is out in the bottom part.

So there is a buoyancy force (the 5 cubes) that will pull up, the weight forces of the cubes (rope volume and weight negligible) that go downwards, and the opposing force at the bottom, in the seal for the cube that is out. This force is caused for the column of water.

The result of all this forces doesn't allow the bottom cube to penetrate completely (case impossible). Is the buoyancy force sufficient to lift the bottom cube into the water, given that the column of water is pressing down on the seal? If the cube does get pulled up, then how far?

• Thank you EnergyNumbers, very kind. Here's the link: IMAGE 1 i39.tinypic.com/30ic4s6.jpg IMAGE 2 i43.tinypic.com/mwuopj.jpg and a video too youtube.com/watch?v=JrhurV3pp1I Jun 8, 2013 at 10:28
• Ok Energy. Thanks for pacience and explaining how it goes in this forum. I will add, my road, but i think i will be wrong. Jun 8, 2013 at 11:27
• That's ok: we're here to explain the concepts to each other: so if you set out your calculations, we can see where, if anywhere, you're going wrong, and set out the right concepts for you then to get the calculation right. Jun 8, 2013 at 11:51
• Here Energy, thank you!: oi39.tinypic.com/2vd0ht4.jpg Jun 8, 2013 at 13:03
• I have 3 more images.A real case, do thes computation convince you ? IMAGE1 oi43.tinypic.com/2yukin5.jpg IMAGE2 oi40.tinypic.com/2vdi7ub.jpg IMAGE3 oi40.tinypic.com/nf5u13.jpg Jun 12, 2013 at 9:31