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measurement . -a way to describe the world with numbers Answers questions: how much? How long? How far? Describe the amount; cost; distance; volume; mass; how fast; age Information described with numbers. Estimation . Helps you make a rough measurement of an object by guessing
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measurement • -a way to describe the world with numbers • Answers questions: how much? How long? How far? • Describe the amount; cost; distance; volume; mass; how fast; age • Information described with numbers Chapter 2 Vocabulary/Notes
Estimation • Helps you make a rough measurement of an object by guessing • Based on experience • Useful when you are in a hurry and exact data is NOT required • Improve with experience, practice, and understanding Chapter 2 Vocabulary/Notes
Using Estimation • You can compare an object whose length you don’t know to familiar objects • Often use the word “about” • Also used to check that an answer is reasonable • 1 m = about height of a door knob above the floor • 1 cm = about the width of your smallest finger • 1 mm = about the thickness of a dime Chapter 2 Vocabulary/Notes
Precision • Describes how carefully you make your measurement • The tool used determines the precision of the measurement • The more improved the tool the more précised the measurement • Can be reproduced or copied Chapter 2 Vocabulary/Notes
accuracy • Compares a measurement to the real value • The more accurate the measure, the closer it is to the true value Chapter 2 Vocabulary/Notes
Steps in Rounding • Not all measurements must be measured with great precision • 1. Look at the digit to the right of the place being rounded • The digit remains the same if the digit to the right is 0, 1, 2, 3, or 4 • Round up if the digit to the right is 5, 6, 7, 8, or 9 2. The remaining digits to the right of the rounding place are eliminated from the rounded answer if it is a decimal Chapter 2 Vocabulary/Notes
SI • Means International System of Units • Established in 1960 • General system for measurement • To avoid confusion, scientists use this common language • Worldwide standard of physical measurement for industry, science, and commerce • Uses units such as meters, cubic meter, grams, and Kelvin • Uses multiples of 10 • To convert between units you multiply or divide by powers of 10 Chapter 2 Vocabulary/Notes
length • Distance between two points • Use the meter unit to measure Chapter 2 Vocabulary/Notes
volume • Amount of space an object occupies • Cubic meter (cm3) is used • Formula: Volume=length x width x height or V = l x w x h or V = (l)(w)(h) • Liquid volume is measured using liter • 1 cm3 = 1 mm of water Chapter 2 Vocabulary/Notes
mass • Measures the amount of matter in an object • Uses kilogram unit • 1 L of water = 1 kg • Use a pan balance to measure • Pan balance compares an object to a known mass; it is balanced when the masses on both sides are equal • Depends on the amount of matter in an object • NEVER changes • Mass and weight ARE NOT the same Chapter 2 Vocabulary/Notes
Weight • Measurement of force • Depends on gravity • Can change depending on where the object is located • Spring scale measures weight; the reading on the scale depends on the force pulling the spring Chapter 2 Vocabulary/Notes
temperature • Measures how hot or cold an object is • In SI it is measured with the Kelvin (K) scale • Measured also in Fahrenheit or Celsius • 273 K = 0°C = 32°F (freezing point of water) • 373 K = 100°C = 212°F (boiling point of water) • Zero Kelvin is the coldest temperature possible in nature Chapter 2 Vocabulary/Notes
Time • interval between two events • Measured in seconds (s) or hours (h) Chapter 2 Vocabulary/Notes
rates • A ratio of two measurements with different units • Example: speed-distance traveled in a given time • Measured in kilometers per hour (km/h) • Are combinations of units Examples: grains/liter; °C/hour Chapter 2 Vocabulary/Notes
photographs • Shows an object exactly as it is • Movie show can be slowed down or speeded up Chapter 2 Vocabulary/Notes
drawings • Can show important things and leave out unimportant details • Illustrations • Can show things we can’t photograph • Can show hidden things • sketches Chapter 2 Vocabulary/Notes
Tables • Organized way to collect and display data • Displays info in rows and columns so it’s easier to understand Chapter 2 Vocabulary/Notes
graphs • Show the relationships between the data • Used to collect, organize and summarize data in a visual way • Can display one set of data or more • Three common types: -line graphs -bar graphs -circle graphs Chapter 2 Vocabulary/Notes
Line graph • Has two variable (something that can change or vary) • Used to show the relationship between two variables • Both variables must be numbers • Has a vertical axis and a horizontal axis (bottom line) Chapter 2 Vocabulary/Notes
Bar Graph • Uses bars to show the relationships between variables • One variable MUST be a number; the other variable is divided into parts Chapter 2 Vocabulary/Notes
Circle Graph • Shows the parts of a whole • The circle represents the whole • Sections represents the parts • All the sections together equal 100 percent Chapter 2 Vocabulary/Notes
Misleading Graphs • The way you mark the scale on a graph can create the wrong impression • A broken scale (on the vertical axis) is used for small but significant changes Chapter 2 Vocabulary/Notes