Metric Measurement

The metric system was created to develop a unified, natural, universal system of measurement. In 1790 King Louis XVI of France assigned a group to begin this task. As of 2005, only three countries, the United States, Liberia, and Myanmar, have not changed over to the metric system. The official modern name of the metric system is the International System of Units or abbreviated SI. History The SI system is used universally for all scientific purposes so the metric system will be the only system of measurement we will be using in science this year.

The metric system was developed based on decimals The metric system was developed based on decimals. The base units are converted by factors of 10 by simply moving the decimal place. A prefix is then added to the base unit to indicate a larger or smaller unit. The base unit for length is the meter. The meter was originally defined as 1/10,000,000th of the distance from the North Pole to the Equator through Paris. The meter is now defined as the distance traveled by light in an absolute vacuum in 1/299,792,458 of a second (don’t worry – you don’t have to remember this).

The base unit for mass in the metric system is the gram The base unit for mass in the metric system is the gram. Mass is a measurement of how much matter is in an object. Mass is measured using a balance. One gram is about the same as a small paper clip. Double pan balance Mass of about one gram Triple beam balance

Volume is the measurement of how much space an object occupies Volume is the measurement of how much space an object occupies. Liquid volume is measured with a graduated cylinder. Solid volume can be calculated with a formula or by water displacement. The basic unit for volume in the metric system is the liter. One liter sodas can be purchased at convenience stores. Water displacement Graduated cylinder Volume formula for a rectangular prism is length x width x height.

Temperature is the measurement of the heat of something on a scale Temperature is the measurement of the heat of something on a scale. The basic unit of temperature in the metric system is Celsius or centigrade. Water freezes on the Celsius scale at 0° and boils at 100°. Temperature is measured with a thermometer. Thermometer Water at freezing point measured by a digital thermometer

Prefix kilo hecto deka deci centi milli The metric system uses prefixes added to the base unit to represent larger or smaller units. Each prefix is a multiple of 10. Prefix Abbreviation Word value Number value kilo km one thousand 1000 hecto hm one hundred 100 deka dam ten 10 deci dm one tenth 0.1 centi cm one hundredth 0.01 milli mm one thousandth 0.001

Length Units in Metric System Most Common Mass Units in Metric System kilometer hectometer dekameter meter decimeter centimeter millimeter kilogram gram milligram Most Common Volume Units in Metric System liter milliliter

Metric mass can be expressed in terms of metric volume Metric mass can be expressed in terms of metric volume. One gram of mass equals one milliliter in volume. One milliliter equals one centimeter cubed. If one milliliter equals one gram then 1000 milliliters or 1 liter equals 1000 grams or 1 kilogram. kilogram/liter

Significant Figures The idea of significant figures or significant digits is a method of expressing error in measurement. You get significant figures by measuring a value and then estimating one degree beyond the limit of the reading; for example, if an object, measured with a ruler marked in millimeters, is known to be between six and seven millimeters and can be seen to be approximately 2/3 of the way between them or a little more than half way, an acceptable measurement for it could be 6.6 mm or 6.7 mm. The .6 or .7 is estimated. This shows that the 6 millimeters is known and that the measurement was a little bit more than that. By using significant figures correctly, you are increasing the accuracy of your measurements. In the example from above, if the object measured with a ruler in millimeters was exactly on 6 millimeters, then to show significant figures you would express the measurement as 6.0 millimeters. Zeroes are significant when placed after a decimal. This demonstrates the degree of accuracy you are using and anyone viewing your data would understand how accurate your measurement was.

A meniscus (from the Greek for "crescent") is a curve in the surface of a liquid and is produced in response to the surface of the container or another object. It can be either concave or convex. A convex meniscus occurs when the molecules of the liquid repel the molecules of the container or object. This may be seen between mercury and glass in barometers. Oppositely, a concave meniscus occurs when the molecules of the liquid attract those of the container. This can be seen between water and glass. You will be observing liquids with a concave meniscus in sixth grade. When measuring liquids you will have to keep in mind significant figures while reading the bottom of the meniscus. The volume of the liquid using significant figures is 40.76 mL.

Using a Graduated Cylinder 1. A graduated cylinder is used to find the volume of a liquid. The volume tells you how much space that liquid occupies. 2. The marks on the cylinder are called graduations. That is why the instrument is called the graduated cylinder. Each mark on this cylinder is worth one milliliter, a basic unit of measure for the volume of a liquid. A unit for larger volumes is the liter. 3. The graduations on a cylinder are not always worth the same. Before using the cylinder, you need to figure out what each graduation is worth. 4. When a liquid is put into a cylinder, the surface curves. This curve is called a meniscus. When reading the volume of a liquid, always read at the bottom of this curve while placing the container on a flat surface and bending down to look at the meniscus at eye level. 5. The abbreviation for milliliter is mL. A capital L is used so that it is not confused with the number "1". 6. The lettered arrows on the diagram to the left point to volume measurements. Arrow "A" reads 48 mL. Write the answers to the other arrows on a piece of paper. Check your answers with on the next page. To go to the next page, click on the right arrow key.

Answers for reading a graduated cylinder 48 mL 45 mL 38 mL 27 mL 18 mL To go to the next page, click on the right arrow key.

Determining the Graduations on a Graduated Cylinder

Check you answers on the next page. To go to the next page, click on the right arrow key.

Answers to determining the scale of a graduated cyclinder. 1 mL 0.5 mL To go to the next page, click on the right arrow key.

Using a Triple Beam Balance beams riders rider measurement tray zero mark pointer adjustment knob The balance has three beams called rider beams. Each rider beam has a different mass suspended from it. These masses, called riders, can be moved left and right along the rider beams. By moving the riders, you can determine the mass of an object placed on the measurement tray.

zero mark pointer adjustment knob An adjustment knob is used to calibrate the balance. When no objects are sitting on the measurement tray, and all the riders are in their leftmost or 0 position, the pointer should be lined up with the zero mark. If it is not lined up with the zero mark, you would need to turn the adjustment knob until it is.

To find the mass of an object using a triple beam balance, place the object on the measurement tray and adjust the positions of the three riders on the rider beams until the pointer lines up with the zero mark. The mass of the object can then be found by adding the values indicated by the three riders. measurement tray Practice reading a triple beam balance by clicking here!

Using a Double Pan Balance measurement tray adjustment knob rider beams riders Additional mass weights pan zero mark pointer The double pan balance has two beams called rider beams. Just like on the triple beam balance, these rider beams have a different mass suspended from them. These masses, called riders, can be moved left and right along the rider beams. By moving the riders, you can determine the mass of an object placed on the measurement tray. An adjustment knob is used to calibrate the balance. When no objects are sitting on the measurement tray, and all the riders are in their leftmost or 0 position, the pointer should be lined up with the zero mark. If it is not lined up with the zero mark, you would need to turn the adjustment knob until it is. To find the mass of an object using a double pan balance, place the object on the measurement tray and adjust the positions of the two riders on the rider beams until the pointer lines up with the zero mark. The mass of the object can then be found by adding the values indicated by the two riders. If the object being massed needs more mass weights to balance the balance, mass weights can also be placed on the right pan and then added to the values of the 2 riders.