For example, kilo- denotes a multiple of a thousand, so there are one thousand meters in a kilometer. Milli- denotes a thousandth; therefore, there are one thousand millimeters in a meter. Prefixes for SI units : The prefixes redefine the measurement as either a multiple or a fraction of the basic unit. Keep in mind that prefixes should never be combined. Thus a millionth of a meter is a micrometer , not a millimillimeter, and a millionth of a kilogram is a milligram , not a microkilogram.
In older usage, a micron a measurement often encountered in physics and engineering is the same as a micrometer, 10 -6 meters. Another older form of usage, the millimicron, is one thousandth of a micrometer, or 1 thousandth of 10 -6 meters, or 10 -9 meter, now called a nanometer. While these older terms are not in common usage, they are often encountered in older publications, and knowing their modern equivalents is an advantage. The properties of a material may be described in many ways.
Any amount of any substance will have a volume. If you have two containers of water that are different sizes, they each hold a different amount, or volume, of water.
The unit for volume is a unit derived from the SI unit of length and is not a fundamental SI measurement. If two water samples have different volumes, they still share a common measurement: the density.
Density is another measurement derived from SI basic units. The density of a material is defined as its mass per unit volume. In this example, each volume of water is different and therefore has a specific and unique mass. The mass of water is expressed in grams g or kilograms kg , and the volume is measured in liters L , cubic centimeters cm 3 , or milliliters mL.
The measuring cup : The measuring cup is a common household utensil used for measuring the volumes of liquids. If you have ever cooked in a kitchen, you have probably seen some sort of measuring cup, which allows the user to measure liquid volumes with reasonable accuracy.
The measuring cup expresses liquid volume in the standard SI units of liters and milliliters. Most American measuring cups also measure liquid in the older system of cups and ounces.
Scientists who work in a laboratory must be familiar with typical laboratory glassware, often called volumetric glassware. These may include beakers, a volumetric flask, an Erlenmeyer flask, and a graduated cylinder. Each of these containers is used in a laboratory setting to measure liquid volumes for different purposes. Laboratory volumetric glassware : Glassware, such as these beakers, is commonly used in a laboratory setting to conveniently measure and separate different volumes of liquids.
Different substances have different densities, so density is often used as a method to identify a material. Comparing the densities of two materials can also predict how substances will interact.
If the object has a lower density than water, it will float to the top of the water. An object with a higher density will sink.
Air has a density of approximately 1. He summons Archimedes, who decides to use density to determine the metal. But how can he determine the volume of the crown? Liquids tend to form layers when added to water. Vegetable oil approx. Water itself is a complicated and unique molecule. Recall that the three basic forms of matter are solid, liquid and gas ignore plasma for the time being. As a rule of thumb, almost all materials are more dense in their solid or crystalline form than in their liquid form; place the solid form of almost any material on the surface of its liquid form, and it will sink.
Water, on the other hand, does something very special: ice the solid form of water floats on liquid water. At that point, the density trend reverses. The implications of this simple fact are enormous: when a lake freezes, ice crusts at the surface and insulates the liquid below from freezing, while at the same time allowing the colder water with a temp of approx.
If ice did not float, it would sink to the bottom, allowing more ice to form and sink, until the lake froze solid! As a result, liquid water always exists in lakes and rivers during the winter months.
This unique property of water enables animals and plants to survive under the frozen lake or winter, ensuring that all freshwater life does not go extinct each winter. The ability to measure temperature accurately was a major scientific advancement, putting absolute numbers on an observable phenomenon. How hot was it last summer? Will it be cold enough for skiing next week? Each of these questions forces quantification to a routine experience. To know this, one must be able to put some sort of accurate number on the concept.
Although there is an entire field of study devoted to measuring temperature thermometry , the focus of this section is on the fundamental measurements of temperature. Monthly mean temperature : Temperature enables us to accurately measure and compare climates in different parts of the world. To people in the 21 st century, measuring temperature is a quick and easy thing to do.
A few years back, we were living in a foreign country and my appendix flared up. Long story short, it had to be removed. There was no time to weigh me beforehand, so the anesthesiologist asked me how much I weighed. And I gave my answer in pounds. They used the metric system, which meant that my weight should be given in kilograms. The doctor replied that there was no way I weighed that much. This time she asked, "What is your weight in kilos?
And that's when my high school chemistry teacher flashed into my mind's eye - 1 kilo equals 2. I did a bit of quick math in my head and answered her question. Luckily my math was right, the anesthesiologist was able to give me the right dose for surgery, and I'm here today partly because I knew how to convert pounds to kilograms in a moment.
Now, I know that my story is a bit dramatic and not all of your students will be in a foreign country needing to convert their weight in an emergency situation. But units of measurement and knowing how to convert them is super important to science. So, I wanted to take a moment to share a bit more about units, along with some of the key conversion factors your students should memorize. And, then we'll wrap it all up with a free printable you can use with your students to practice all this.
I am a bit of a stickler on units of measurement thanks to my high school chemistry teacher. She always told us that a number in chemistry meant nothing without its units, which is so true. After all, if I say that I need 2 of sugar for a recipe, do you know if I mean 2 tablespoons, 2 grams, 2 cups or 2 kilos?
SI Conversion Calculator. We would like to acknowledge that Douglas College campuses, where we live, learn, work and play, are located on the unceded traditional territories of the Coast Salish Peoples of the QayQayt and Kwikwetlem First Nations. Library Coquitlam. Phone: Learning Centre New Westminster. Email Us. Today's Hours Library Coquitlam. Site Search. Measurements and Units. Item request has been placed! Item request cannot be made. Processing Request.
Measurements and Units Accuracy, Precision, and Errors A measurement is a quantitative observation that consists of two parts: a number and a unit. These are some fundamental quantities in the SI system: Physical Quantity Unit Abbreviation Length meter m Mass kilogram kg Time second s Temperature kelvin K Number of particles mole mol Electric current ampere A Luminous intensity candela cd All other physical quantities have units that can be derived from the SI base units.
Conversion factors It is often necessary to convert a given result from one SI unit to another e. Essentially, conversion factors are the ratio between two units. Dimensional Analysis It is often necessary to convert a given result from one SI unit to another e. There are cases where the units of both the numerator and denominator must be converted. Desired units Cancelling out units is a way of checking out that your calculation is set up correctly.
Conversion factors can be raised to other powers. Measuring Properties of Matter Basically, the properties of matter can be classified into two groups: extensive and intensive properties. Mass vs. Weight Mass m is the quantity of matter in an object.
Mass Weight Mass is always a constant at any place and time Gravity changes and depends on gravity at the place Is measured in Kilograms SI system Is measured in Newtons Can never be zero Can be Zero with no gravity Is an intrinsic property of an object and is dependent of any external factor Depends on: Mass of the object Force and gravity Volume Volume is the amount of space that an object occupies.
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