Archimedes Principle for kids
What is the connection between people putting bricks in their toilets and Archimedes principle?
Archimedes’ principle is better known as the law of buoyancy.
It states:
Something submerged(partially or fully) in water experiences a force that tries to push it up (and out of the water).
The amount of that force is exactly equal to the WEIGHT of the WATER that the object is displacing.
Back to the submerged bricks…
Assuming a brick is 4″ x 2″ x 8″ you can determine the buoyant force on the brick as follows:
(1)Make a box the exact same size as the brick.
(2)Fill it with water
(3)Weigh the water.
Let’s say that the water weighs 1 kilogram.
That means that every brick that is put into the toilet is experiencing an upward buoyant force of 1Kilogram.
Assuming the brick weighs 2 Kilograms, which is greater than the buoyant force, the brick will stay on the bottom of the toilet.
If we try to use a block of wood the same size, that weighs 0.5Kg instead of the brick, that block will be pushed out of the water and float.
How far will the wood block be pushed out of the water?
Until the Volume below the water line is equal would be 0.5kg of Water!
Based on 1Kg for the weight of water that a brick displaces,
we would expect that it would float exactly halfway submerged.