RRCS MOBILE
 BACK VARIOUS NOTES: 'DENSITY and MEASUREMENT' Measurement Notes **IF HIGHLIGHTED, VERY IMPORTANT! PLEASE MAKE NOTE CARDS FROM THE HIGHLIGHTED YELLOW TERMS:Measurement- A way to describe the world with numbers. Estimation- Helps you make a rough measurement of an object. Precision- A description of how close measurements are to each other Accuracy- When you compare a measurement to the real, actual, or accepted value. SI-International System that allows people all over the world to use the same base for measurements. Meter- the SI base for measuring length. (distance) Volume- The amount of space an object takes up. Mass- The measurement of the amount of matter in an object. Gram- The SI base for measuring mass. Weight- The measurement of force (gravity) Rate-The amount of change in one measurement over a period of time Liters- The SI base for volume.(liquid) Centimeter Cubed or CM3 - SI base for volume (solid) Density- A measure of how much mass is continued in a given space I. What do we measure? A. Distance - length, width, height B. Temperature C. Volume D. Mass - related to weight but not the same E. Time F. Speed - distance per time - a CALCULATED UNIT G. Density - mass per volume - a CALCULATED UNIT II. DISTANCE or LENGTH – the amount of space between 2 objects A. What do we measure distance or length with? 1. Meter stick 2. Ruler 3. Tape measure B. What units do we use to measure distance? 1. Standard or Customary a. Inches, feet, yards, miles b. 12 inches = 1 foot, 3 feet = 1 yard, 5280 feet = 1 mile 2. Metric System - Meter - basic unit of distance - little more than 3 feet a. Deci (d) means .1 of something so a decimeter is .1 of a meter or 10 decimeters equals 1 meter. b. Centi(c) means .01 of something so a centimeter is .01 of a meter or 100 centimeters equals 1 meter c. Milli(m) means .001 of something so a millimeter is .001 of a meter or 1000 millimeters equals 1 meter. d. Deka (da) means 10 of something so a dekameter is 10 meters. e. Hecto(h) means 100 of something so a hectometer is 100 meters. f. Kilo (k) means 1,000 of something so a kilometer is 1,000 meters. *** Metric system is based on a series of 1 to 10 relationships. One of them is that 10 millimeters equals 1 centimeter. III. Volume – how much space an object takes up. A. What do we measure with? 1. Graduated cylinder 2. Beaker 3. Displaced volume – water usually 4. Calculate using dimensions – formula for a box is volume = length * height * width or V=l*w*h B. What units are used to measure volume? 1. Standard or customary are gallons, cups, pints, etc 2. Metric unit is the Liter – basic unit of volume in metric system a. In science we mainly use milliliters or mL. b. The whole unit is based on the amount of water that has a mass of 1 gram – this is how much a milliliter or mL is. c. There are 1000 mLs in a liter or 2000 of them in a 2 liter bottle of Pepsi. d. Graduated cylinders and beakers are marked off in milliliters. IV. Mass – how much matter is in an object. A. What do we measure with? 1. The balance scale – triple beam balance in this class. B. What units are used? 1. The standard unit of pound does not measure mass but rather weight – these might be the same on Earth but weight depends upon gravity so it changes if gravity changes, like in space. 2. Metric unit mass is the Gram. 3. We do most of our measurements in grams – down to the nearest tenth of a gram – this is how accurate the balance scales are. V. Temperature – the amount of thermal energy in an object or substance. A. What do we measure with? 1. A thermometer – usually a metal backed thermometer that uses colored water. 2. Can use large dial thermometers or long glass thermometers. B. What units are used? 1. The standard unit is Fahrenheit. We will not use this unit in class but you should know that water freezes at 32 degrees and boils at 212 degrees. These are hard numbers to remember or work with – this is why the Fahrenheit system is not as good as the metric. 2. The metric unit is Celsius. a. This unit is based on the properties of water – just like volume and mass. The base line for Celsius is the freezing point of water – 0 degrees Celsius. The boiling point of water is 100 degrees Celsius. VI. Time – we will use stopwatches to measure the passing of time – we will measure it in terms of seconds and hundredths of a second. VII. Speed – a calculated unit that determines how far an object goes in a certain period of time. A. A calculated measurement is one that you do not measure directly but have to use a formula to determine B. The formula for speed is distance divided by time C. The units for speed are a combination of a distance and time - for example – 32 meters per second or 65 miles per hour VIII. Density – a calculated measurement that determines an objects mass for a certain amount of volume. A. To calculate density you must use the following formula – mass divided by volume = density. B. The units for density are a combination of a mass unit and a volume unit. The most common density unit is grams per milliliter (g/mL). C. We determine density by using a balance scale and a graduated cylinder and then dividing the measurements. D. The great thing about density is that it does not depend on the size of an object – all pieces of gold, no matter how big or small, have the same exact density. E. This makes density useful in determining what an object is made of – if you know the density, you can compare it to known densities and figure out what its made of.
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