The toilet is wet and moist, with water in and out through pipes and sewers. Sometimes, you have puzzled experience there, especially, in the hand basin, toilet bowl and shower curtain, etc. In this chapter, the hidden science will be revealed and you will have a better understanding on them.
The Swirling of Water in a Basin |
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How Things Work |
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Insight |
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Apparently, objects stay on the ground travel the same speed as the ground. As a result, there is no Coriolis effect. For example, a stationary object on the Earth does not exhibit such effect, because the object velocity relative to the Earth is zero. |
The Flush in a Toilet Bowl |
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The bowl of a flush toilet is a porcelain (pottery made of a special white clay) vessel with a built-in siphon, usually visible (sometimes hidden in some toilet bowls) as a curved pipe protruding from the back. In most toilets, the bowl has been molded so that the water released from the tank enters the rim and it drains out through the holes in the rim. Normally, the bowl contains a small amount of water which is enough to form an air trap inside the siphon pipe, preventing foul air escaping from the sewer.
When the toilet is used, liquid flows slowly through the siphon pipe as waste matter is added, but the flow
volume is too small to fill the siphon. To flush the toilet, the user activates
the water tank which pours a large quantity of water quickly into the bowl. This creates a flow large
enough to fill the siphon pipe, causing the bowl to empty rapidly due to the weight of liquid in the pipe.
The flow stops when the liquid level in the bowl drops below the first bend of the siphon, allowing air to
enter which breaks the column of liquid.
In this section, we are not interested in the refill mechanism in the tank but instead the siphon in the toilet bowl.
The crucial mechanism is called the bowl siphon which is shown in the following animation (Credit: Marshall
Brain's How Stuff Works).
How Things Work | ||
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The flushing mechanism is summaried in the following points.
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Science in Depth | ||
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Shower Curtain |
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How Things Work | ||||
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There are two possible answers that explain the phenomenon.
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Insight | ||||
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Science in Depth | ||||
Bernoulli's effect is the result of conservation of energy. As a simple illustration, consider a running fluid
through a horizontal pipe which has a narrow constriction on the flow path.
The fluid moves faster on the narrow constriction, but at the same time we find a lowering of fluid pressure there.
In general, a flowing fluid can be considered having energies due to two parts, namely, the potential energy
and the
kinetic energy (the third term in the following equation).
The former is static in sense, while the latter is dynamic as it relates to the
velocity of fluid.
The potential energy includes two components, the gravitational potential energy (second term in the following
equation) due
to its altitude and the pressure energy (the first term in the following equation)
due to the pressure the fluid experiences. Specifically, the gravitational
potential is considered when the fluid is running through an inclined pipe.
The equation above is the well-known Bernoull's equation, it states clearly that the total energy per unit volume in a flowing fluid is a constant. The Bernoulli's effect is widely applied in aerospace engineering, for example the design of airfoil.
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