why do rocks sink and supertankers foat?

Question

it's for a sience fair project and i can't find answers on the web

Answer 1

Rocks have a much higher density than water, and supertankers have special buoyancy glands internally that contain lots of air so it can float, just like fish can maintain a certain buoyancy in the water. Rocks don't have that, obviously.

Answer 2

Rocks sink because they do not have a way of "Floating" on the water. They do not have deep bottoms with tall sides, and they are not hollowed out. (I.e. no air inside them)

Boats, no matter the size float because they displace water around them. The water has no way of getting into the boat because the sides of the boat prevent it from doing so.

With nowhere for the water to go, inside the boat, it remains afloat.

The more cargo a ship will be carrying, the wider and deeper it needs to be otherwise it will fall below the water level, take on water, and sink.

An experiment...

Put a rock in a bucket of water. It will sink.

Put the same rock insider of a baloon, blow the baloon up slightly (Doesn't have to be all the way) and tie it closed.

Put that in the bucket and it will float as long as there is enough air to keep the top of the balloon above water.

Too little air, and it will still sink.

There is an air pocket inside the baloon that the water cannot get into, therefor, the displaced water has no where else to go, so it tries to resist the baloon and keeps it floating.

Answer 3

water displacement
if a rock was wide enough to displace enough water and was of a given density relative to the water, it would float, but rock are dense objects for there size, and do not displace enough water when submerged for the pressure of the water to push on the sides and bottom to float them. a supertanker or any ship displaces water, since the ship are not 100% solid , there density per water displaced is low, but there is a given amount of width and depth ( total area ) needed to offset the tonnage when desging a ship so that fuly laden al lthe wate they displace will have enough force to hold the ship afloat, this is also why even when a ship hasa hole in the hull, there are water tight compartments in case of flooding to still keep a ship afoat, however there is only so much water than can bridge a hull before the weight starts to become equalized and the ship will begin to sink at that point

Answer 4

because of the density.The rock is density than water so it sink. The supertankers is density than water so it float.


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Answer 5

Rocks sink because they weigh more than the volume of water they they displace.

Supertankers float because they weight less than the volume of water that they displace.

Answer 6

Density.