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A Satellite Of Our Own

The regular daily and monthly rhythms of Earth's only natural satellite, the Moon, have guided timekeepers for thousands of years. Its influence on Earth's cycles, notably tides, has also been charted by many cultures in many ages. More than 70 spacecraft have been sent to the Moon; 12 astronauts have walked upon its surface and brought back 382 kg ...

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ASatelliteOfOurOwn
Mathematics

How To Calculate The Circumference Of A Circle

A circle is what you get if you take a straight line and bend it around so that its ends touch. You can demonstrate this by taking a piece of stiff wire and doing just that: bring the ends of the wire ... Continue reading

CircumferenceOfACircle
Chemistry

Ozone: Good Up High, Bad Nearby

Ozone is a gas that forms in the atmosphere when 3 atoms of oxygen are combined (03). It is not emitted directly into the air, but at ground level is created by a chemical reaction between oxides of ... Continue reading

Ozone
Engineering

The Right Stuff for Super Spaceships

Revolutions in technology - like the Industrial Revolution that replaced horses with cars - can make what seems impossible today commonplace tomorrow. ... Continue reading

SuperSpaceships
Astronomy

Solar Spitwads

Take a piece of paper. Make a little wad. If you're a kid, spit on it. Put it in a straw and blow hard. If your teacher sends you to the principal's office, here's your excuse: you were making a model ... Continue reading

SolarSpitwads

Ants Are Wimpy

AntsIt's common knowledge that ants can lift many times their own weight. We are frequently told they can lift 10, 20, or even 50 times their weight. It is most often stated something like this: an ant can lift over its head objects that weigh 20 times what the ant weighs. This is the equivalent of a 220 pound (100 kilogram) man lifting over 4,400 pounds (2000 kilograms) over his head! Seems incredible, doesn't it? That's like lifting a new VW Beetle, with five big men inside, over your head. A person who could do that would be a superman!

Are ants superstrong then? No. The reason they can lift so much more than they weigh is because they are very small. If we were that small, we could do it too. A small animal lifting many times its weight is not the same as a large animal lifting many times its weight. The reason has to do with simple geometry and the characteristics of muscles.

As an animal, or any object, grows in size, its volume and weight increase much faster than its height. If a 220 lb (100 kg) man were to grow ten times taller, his weight would increase by a factor of 1000 (the cube of his height). He would weigh 220,000 lbs (100,000 kg)! The strength of his muscles, on the other hand, would increase by the square of his height, or by a factor of 100. He would be 100 times stronger but 1000 times heavier. His muscle strength could never grow as fast as his weight. It's simple geometry. There is little reason, then, to compare the strength of small animals to big animals when it comes to how much more than their weight they can lift.