rafnagud9 Posted November 6, 2008 Share Posted November 6, 2008 The United Nations estimates that there are in excess of 100,000,000 child slaves on the planet (this number doubles for children between the ages of 5-17 who are considered indentured servants). Link to comment Share on other sites More sharing options...
Mary Hartman Posted November 11, 2008 Share Posted November 11, 2008 How can hummingbirds fly upside-down and backwards? Hummingbirds use enormous amounts of energy simply being themselves. When a hummingbird is sitting quietly on a branch, its heart beats a staccato 550 times a minute. When a bird is engaged in aerial acrobatics, its heart can speed up to 1,200 beats a minute. A person whose body burned energy at the rate of a hummingbird would have to eat about 155,000 calories a day. In fast food, that's the equivalent of about 287 Big Macs. But hummingbirds prefer nectar to burgers. So instead of hovering at the nearest drive-through window, a hummingbird helicopters alongside a flower. Just as a helicopter can perform feats that put ordinary planes to shame, so hummingbirds can fly rings around other birds — including upside down and backwards (although not in heels). Most birds fly by flapping, moving their wings forward and downward with great force. A bird's flight muscles are specialized chest muscles (pectorals), souped-up versions of human pecs. The average bird's "upstroke" muscles are weak, weighing only 5 to 10 percent as much as its powerful downstroke muscles. But hummingbirds are built for acrobatics. A hummingbird's pecs make up nearly a third of its body weight, compared to 15 to 20 percent for other birds. (Imagine a 180-lb. body-builder — with 60-lb. pecs). And a hummingbird's upstroke muscles are as big and powerful as its downstrokes. Like a regular bird, a hummingbird flaps his or her wings to fly forward. But a hummingbird's wings rotate at its flexible shoulders nearly 180 degrees. Meanwhile, the tiny bird's wings beat about 18 to 80 times a second. (Compare that to a vulture's once-a-second flap.) By slanting the angle of its wings and using its powerful chest muscles, a hummingbird can tip up and fly backwards. And by spreading its tail and doing a quick backward somersault, a hummingbird can also fly upside down (a position in which its improved upstroke — now a downstroke — becomes important). Finally, a hummingbird can hover. It does so tilting its body nearly straight up and down, while moving its wings forward and backward in a figure-eight. In addition, like a helicopter, a hummingbird can lift straight up into the air. Recent studies have revealed that hummingbirds combine a bird's body with the flying tricks of insects, like the hover-and-dart motions of dragonflies. Researchers used microscopic droplets of olive oil, tiny enough to float and move in air. With a laser lighting the droplets, the researchers used an ultra-fast camera to capture the air patterns left in a hovering hummingbird's wake. Insects have nearly flat wings, and use a figure-eight wing pattern that creates nearly equal lift during downstrokes and upstrokes. Bird wings are more like human arms than insect wings. And a hummingbird is no match for an insect, since about 75 percent of its weight support, according to the researchers, comes from the downstroke. But other birds' in-flight weight support comes almost 100 percent from the downstroke. The 25 percent lift on the upstroke gives hummingbirds their insect-like hovering advantage. *Pic added at edit Link to comment Share on other sites More sharing options...
leddy Posted January 13, 2011 Share Posted January 13, 2011 Did you know that the name "Axl Rose" is an anagram Link to comment Share on other sites More sharing options...
Broken Levee Posted January 14, 2011 Share Posted January 14, 2011 Do forgive me if someone has already posted this but, has everyone heard of the new zodiac sign Ophiuchus? Apparently that makes me a Taurus now. I don't care about any new zodiac sign, I'm a Gemini. Always have been, always will be. Link to comment Share on other sites More sharing options...
Virginia Posted January 14, 2011 Share Posted January 14, 2011 Do forgive me if someone has already posted this but, has everyone heard of the new zodiac sign Ophiuchus? Apparently that makes me a Taurus now. I don't care about any new zodiac sign, I'm a Gemini. Always have been, always will be. I saw people posting things on Facebook; I haven't checked it out yet though. Link to comment Share on other sites More sharing options...
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