How To Calculate The Volume Of A Cylinder

Calculating the volume of a cylinder is even easier than calculating its area. All you have to do is recognize that a cylinder is no more than just a bunch of circles stacked to a certain height, just like a cube is just a bunch of squares stacked up one on top of the other, and every circle in the stack is identical. The area of each circle is ...

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Ancient Planet

Long before our Sun and Earth ever existed, a Jupiter-sized planet formed around a sun-like star. Now, almost 13 billion years later, NASA's Hubble Space Telescope has precisely measured the mass of ... Continue reading


Fiber Optics

The sun is shining; it's a brilliant day. The springboard flexes powerfully under your feet as you launch into a graceful arc through the air and into the crystal clear water below. Arms extended, you ... Continue reading


New Ideas About An Old Puzzle

There's a familiar way of talking about language as a 'tool,' but of course that's just a metaphor. Literal tools made of rock can last for millennia as evidence of the skills of early humans. Not so ... Continue reading


Finding Ice In The Rocks--Evidence Of Earth's Ice Ages

In the late 1700s, geologists began trying to determine how huge boulders of granite weighing several tons could have moved as much as 80 km (50 miles) from their origins in the Swiss Alps. Some ... Continue reading



AlloysWater is a clear colorless liquid. So is methanol. If one were to take a quantity of methanol and pour it into some water, the result is also a clear colorless liquid. But this one is something new; a solution, an intimate physical combination of both materials. This simple illustration demonstrates some characteristic properties of solutions. To form a solution, the combined materials must be compatible and able to mix completely with each other. The component molecules that make up a solution become intimately mixed with each other in an even and consistent manner. In a proper solution there are no regions in which the concentration of any component is significantly different from any other region. To all intents and purposes, a solution looks and acts very much like a single material. Solutions are not restricted to the liquid phase. They can also be gaseous or solid. But whether solid, liquid, or gas in physical state, the basic defining properties of a solution remain the same.

Solutions made from combinations of different metals are called 'alloys'. One metal is said to alloyed with another, meaning only that the two (or more) metals have been melted and blended together in the manner of a solution. When the molten solution solidifies, the properties of the solution are 'trapped' in the solid form. As one might expect, there is an infinite range of possible combinations of the metals in any particular alloy. Brass, for example, is an alloy of copper and zinc. The possible combinations can range from pure copper (100% Cu and 0% Zn) to pure zinc (0% Cu and 100% Zn) in a continuous gradient. Any particular combination produces a brass having fairly well-defined properties of hardness, ductility, malleability, corrosion resistance, color, etc.

One property in particular is most controllable in alloys: the melting point. Each component metal of an alloy has its own melting point, but the alloy itself will have a lower melting point than any of its component metals, and melting will generally occur over a span of several degrees. Alloys can then be 'designed' to produce a material that better conforms to the conditions under which it will be used. An interesting feature of alloys is the lack of certain combinations, such as alloys of aluminum and lead. These, and others, are unknown as bulk alloys because the component metals act like 'oil and vinegar' and do not mix with each other to produce a proper alloy. In molten form, lead and aluminum separate spontaneously. Any solid alloys of these two metals may be made only in very small quantities by depositing them from the gas phase simultaneously.