Description and Measurement Chapter 2:1 Measurements Description and Measurement Chapter 2:1

A way to describe the world with numbers Measurement A way to describe the world with numbers Answers questions such as how long, how much, or how far.

Estimation A rough measurement of an object You use prior knowledge to help you with an estimation Comparison is a good way to create an estimation Used to check if your answer is reasonable

Precision and Accuracy Precision is a description of how close measurements are to each other There are degrees of precision Accuracy is when you compare a measurement to a real, actual, or accepted value.

Rounding If the digit to the right is 0,1,2,3, or 4, the digit being rounded stays the same If the digit is 5,6,7,8, or 9, the digit rounded increases by 1 The digits to the right of the digit being rounded to are deleted if they are also to the right of the decimal. If they are to the left of the decimal, they are changed to zero. How we would round 1579.254 28.888 17359.8882

Significant Figures The number of digits that truly reflect the precision of the number are called significant figures. They are figured as follows: Digits other than zero are ALWAYS significant Final zeros AFTER a decimal point ARE significant {6.545600g} Zeros BETWEEN other digits ARE significant {507.0301g} Intial (beginning zeros) are NOT significant {0.0002030g} Zeros in a whole number may or may not be significant {1650} A number obtained by counting instead of measuring can have infinite sig. figs.

Rules for Sig. Figs. For multiplication and division, you determine the number of sig figs in each number of your problem. The sig figs of your answer are determined by the number with the fewest digits. EX: 6.14 X 5.6=34.384 For addition and subtraction, you determine the place value of each number in your problem. The sig figs of the answer are determined by the number that is least precise. (using tens, hundredths, etc.) EX: 6.14 + 5.6=11.74

Homework Right Side: Page 49 1-4 Left Side: output of some of your own examples of each rule of significant digits paragraph