PHYSICS AND CHEMISTRY

Absolute zero defined:
Absolute zero is the theoretical temperature at which all substances have zero thermal energy. Originally conceived as the temperature at which an ideal gas at constant pressure would contract to zero volume, absolute zero is of great significance in thermodynamics and is used as the fixed point for absolute temperature scales. Absolute zero is equivalent to 0°K, -459.69°F, or -273.16°C.

Does hot water freeze faster than cold?
A bucket of hot water will not freeze faster than a bucket of cold water. However, a bucket of water that has been heated or boiled, then allowed to cool to the same temperature as the bucket of cold water, may freeze faster. Heating or boiling drives out some of the air bubbles in water; because air bubbles cut down thermal conductivity, they can inhibit freezing. For the same reason, previously heated water forms denser ice than unheated water, which is why hot-water pipes tend to burst before cold-water pipes.

Inertia defined:
Inertia is a tendency of all objects and matter in the universe to stay still, or if moving, to continue moving in the same direction, unless acted on by some outside force.

Does water running down a drain rotate in a different direction in the Northern and Southern Hemispheres?
If water runs out from a perfectly symmetrical bathtub, basin, or toilet bowl, in the Northern Hemisphere, it would swirl counterclockwise; in the Southern Hemisphere the water would run out clockwise. This is due to the Coriolis effect (the Earth’s rotation influencing any moving body of water). Exactly on the equator, the water would run straight down.

The speed of light:
In round numbers, the speed of light in a vacuum is 186,000 miles (300,000 kilometers) per second. The exact figure is 186,282 miles (299,792.458 kilometers) per second.

Primary colors in light:
Color is determined by the wavelength of its light (the distance between one crest of the light wave and the next). Those colors that blend to form “white light” are from shortest wave length to longest: red, orange, yellow, green, blue, indigo, and violet.

The speed of sound:
The speed of sound is not a constant; it varies depending on the medium in which it travels. The measurement of sound velocity in the medium of air must take into account many factors, including air temperature, pressure, and purity. At sea level and 32°F (0°C), scientists do not agree on a standard figure; estimates range from 740 to 741.5 miles (1191.6 to 1193.22 kilometers) per hour. As air temperature rises, sound velocity increases. Sound travels faster in water than in air and even faster in iron and steel. Sounds traveling a mile in 5 seconds in air, will travel the same distance in 1 second underwater and travel 1/3 of a second in steel.

The most abundant chemical element in the universe:
Hydrogen (H, element 1) makes up about 75% of the mass of the universe. It is estimated that more than 90% of all atoms in the universe are hydrogen atoms. Most of the rest are helium (he, element 2) atoms.

The most abundant chemical element on Earth:
Silicon (Si, element 14) is the second most abundant element. Silicon dioxide and silicates make up about 87% of the materials in the Earth’s crust.