Metric

1. Metric Measurement

2. 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.

3. 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).

4. 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

5. 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. 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.

6. 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

7. The metric system uses prefixes added to the base unit to represent larger or smaller units. Each prefix is a multiple of 10.

8. Length Units in Metric System Most Common Mass Units in Metric System Most Common Volume Units in Metric System

9. 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

10. 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.

12. 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.

13. Using a Graduated Cylinder To go to the next page, click on the right arrow key.

14. Answers for reading a graduated cylinder • 48 mL • 45 mL • 38 mL • 27 mL • 18 mL • 7 mL To go to the next page, click on the right arrow key.

15. Determining the Graduations on a Graduated Cylinder

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

17. Answers to determining the scale of a graduated cyclinder. • 1 mL • 0.5 mL • 5 mL • 2 mL • 10 mL To go to the next page, click on the right arrow key.

18. measurement tray beams riders zero mark pointer adjustmentknob rider Using a Triple Beam Balance 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.

19. zero mark pointer adjustmentknob 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.

20. measurement tray 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. Practice reading a triple beam balance by clicking here!

21. pointer zero mark measurement tray Additional mass weights pan adjustment knob riders rider beams Using a Double Pan Balance 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.