Sweet Dolphin Dreams

Imagine if your breathing wasn't an automatic response. That might work during the day. But what about when you went to sleep? You wouldn't get a good night's sleep if you had to wake up every few minutes to consciously take a breath. Luckily for humans, and most mammals, breathing is regulated by our autonomic or involuntary nervous system. ...

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When Do We Encounter Ionizing Radiation In Our Daily Lives?

Everyone who lives on this planet is constantly exposed to naturally occurring ionizing radiation (background radiation). This has been true since the dawn of time. The average effective dose ... Continue reading


Drip, Drip Water Clocks

Water clocks were among the earliest timekeepers that didn't depend on the observation of celestial bodies. One of the oldest was found in the tomb of the Egyptian pharaoh Amenhotep I, buried around ... Continue reading


How To Calculate The Area Of A Right Cone

The cone is another three-dimensional shape based on the circle. You could think of it as the cross between a circle and a right triangle. Its properties will have features of both shapes, and this ... Continue reading

AreaOfARight Cone

Pluto: Beyond Neptune Or Not?

Did I catch you? Pluto (newly classified as a dwarf-planet) comes after planet Neptune. Right? Depends. Pluto takes 248 years to orbit the Sun. Most of that time Pluto's orbit puts it outside the ... Continue reading


Galileo Thermometers

GalileoThermometersEvery substance has the property of 'mass', which is the basic physical presence of matter. Matter occupies space. A physical mass contained within a physical space produces the physical property of 'density'. For practical purposes, we define density as the mass of material contained within a specific unitary volume, usually as grams per cubic centimeter. The density of a material is a reflection of the energy contained by the molecules that compose the material. Molecular energy is exhibited in molecules by various vibrational motions. The more energy the molecules contain, the more they vibrate. The higher the temperature, the more the molecules vibrate and bump into each other. This tends to push teh molecules apart so that fewer of them occupy the same volume of space as the temperature increases.

Thus the mass of any material contained within a unitary volume of space tends to decrease as the temperature increases. Therefore density is inversely proportional to temperature; as temperature increases, the density of materials decreases. Each different material exhibits its 'energy behaviour' in its own unique way. This can be used to correlate the density of a material with its temperature. A Galileo thermometer is constructed using small glass spheres to make a series of floating environments within a larger tube that is usually filled with water. Each sphere contains a specific amount of water and air or another liquid and air, and is tagged with a precisely calibratedcounterweight.

The counterweightis marked with a specific temperature. Each sphere thus has a specific density at a specific temperature. The spheres float within the primary liquid at a level determined by the difference in their densities. Because each of the spheres changes density with temperature at a different rate, the difference between the densities of the two materials decreases in a predictable manner. The level at which any particular sphere floats within the primary liquid changes accordingly. In this way, the temperature is clearly indicated by the sphere floating at the lowest level within the primary liquid.