T1 - (A)-Properties of Materials.doc - T1 - (A)-Properties...

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T1 - (A)-Properties of MaterialsMatteris defined as anything that occupies space and has mass, and it is all around us. Solids andliquids are more obviously matter: We can see that they take up space, and their weight tells us thatthey have mass. Gases are also matter; if gases did not take up space, a balloon would not inflate(increase its volume) when filled with gas.Solids, liquids, and gases are the three states of matter commonly found on earth (Figure 1). Asolidisrigid and possesses a definite shape. Aliquidflows and takes the shape of its container, except that itforms a flat or slightly curved upper surface when acted upon by gravity. (In zero gravity, liquidsassume a spherical shape.) Both liquid and solid samples have volumes that are very nearlyindependent of pressure. Agastakes both the shape and volume of its container.Figure 1.The three most common states of matter are solid, liquid and gas.A fourth state of matter, plasma, occurs naturally in the interiors of stars. Aplasmais a gaseous state ofmatter that contains appreciable numbers of electrically charged particles (Figure 2). The presence ofthese charged particles imparts unique properties to plasmas that justify their classification as a state ofmatter distinct from gases. In addition to stars, plasmas are found in some other high-temperatureenvironments (both natural and man-made), such as lightning strikes, certain television screens, andspecialized analytical instruments used to detect trace amounts of metals.T1 – Properties of Materials1
Figure 2.A plasma torch can be used to cut metal.Some samples of matter appear to have properties of solids, liquids, and/or gases at the same time.This can occur when the sample is composed of many small pieces. For example, we can pour sand asif it were a liquid because it is composed of many small grains of solid sand. Matter can also haveproperties of more than one state when it is a mixture, such as with clouds. Clouds appear to behavesomewhat like gases, but they are actually mixtures of air (gas) and tiny particles of water (liquid orsolid).Themassof an object is a measure of the amount of matter in it. One way to measure an object’s massis to measure the force it takes to accelerate the object. It takes much more force to accelerate a carthan a bicycle because the car has much more mass. A more common way to determine the mass of anobject is to use a balance to compare its mass with a standard mass.Although weight is related to mass, it is not the same thing.Weightrefers to the force that gravityexerts on an object. This force is directly proportional to the mass of the object. The weight of anobject changes as the force of gravity changes, but its mass does not. An astronaut’s mass does notchange just because she goes to the moon. But her weight on the moon is only one-sixth her earth-bound weight because the moon’s gravity is only one-sixth that of the earth’s. She may feel

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