For humans, hearing is normally limited to frequencies between about 12 Hz and 20,000 Hz (20 kHz). Sound with frequencies of less than 20 Hz is known as infrasound. If a sound has a frequency that exceeds 22,000 Hz it is called ultrasound. Sound is transmitted through gases, plasma, and liquids ...
The word "parachute" comes "para", meaning "against" or "counter" in Ancient Greek, and "chute", the French word for "fall" DaVinci sketched the design for the first parachute in 1485. The first user of a man-made parachute was not a man or a woman, but a dog. The inventor of the parachute, a ...
Sweden was home to Alfred Nobel, the inventor of dynamite and other explosives. Prizes first awarded in five subjects: chemistry, physics, physiology or medicine, literature, and peace. Jean Paul Sartre refused the prize for literature in 1964 for fear it would turn him into an institution. Pierre and Marie Curie are ...
Diamond Thieves and Smugglers use homing pigeons to smuggle rough diamonds out of mining areas. About 75% of American brides receive a diamond engagement ring. A new mineral, discovered in Russia, has been named Dianite, after Princess Diana, and it will eventually be polished and mounted in jewellery. The largest diamond ...
If the weather get cold enough that it doesn't snow! Because snow is frozen water, if there are not enough water droplets in the air it can't snow. Snow is not white, is actually clear/transparent. The largest snowflakes in the world fell across Fort Keogh in Montana (USA) on ...
Artificial intelligence is the science and engineering of making intelligent machines, especially intelligent computer programs. It is related to the similar task of using computers to understand human intelligence, but AI does not have to confine itself to methods that are biologically observable. Thinking machines and artificial beings appear ...
Women were banned by royal decree from using hotel swimming pools in Jidda, Saudi Arabia, in 1979. The oldest recorded death sentence is contained in the Amherst papyri, dating to 1500 B.C., which listed Egyptian state trials. A teenaged male, convicted of "magic", was sentenced to kill himself ...
The women of Iceland earn two-thirds of their nation's university degrees. More than half of Indonesia's primary school teachers are under 30years of age . Teachers in China are highly respected. They hardly ever leave the profession and are reasonably paid. In the U.S. the percentage of teachers ...
The constant is called "π" because "π" is the first letter of the Greek words περιφέρεια (periphery) and περίμετρος (perimeter), probably referring to its use in the formula to find the circumference, or perimeter, of a circle. In 1737, Euler used the symbol for pi to be equal ...