# Rate of Sink-Rate of Float

## Does the shape of the object make any difference?

Poll closed Nov 5, 2009.

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4. ### A sphere would sink faster

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1. Oct 26, 2009

### kurtdtn

1. The problem statement, all variables and given/known data

80 m2 Surface Area; 1,519,875 Pascals Pressure; 640 m3 Volume:
2 m x 8 m x 40 m Dimensions; Mass 650,000 kg; and there is 250,000 liters of water inside.

If I let go of the container and allow it to sink what will be the velocity of sinking?
If I pump out 20,000 liters of water so that the container is now buoyant how fast will it rise to the surface?

2. Relevant equations
Weight = mg 650,000 kg * 9.8 m/s = 6374323 N
P =F/A 6374323 N / 80 m2
650,000 kg - 20,000 kg = 630,000 kg
640 m3 of water = 640,000 kg
Mass of Object - Apparent Mass when submerged = Density of Water x Volume

3. The attempt at a solution
650,000 kg - 640,000 kg = +10,000 kg = 10,000/640,000 = 1.6% * 9.8 m/s = .15 m/s upward or downward velocity depending on whether there is 250,000 liters inside or 230,000 liters inside
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution