Warm up: Tuesday, Aug Get out Ch. 1.3 Notes, turn to 1.4, have out HW Set The density of an object was found by using water displacement. The following data was collected (this is in packet). (a) Determine the volume of the object. (b) Calculate the density of the object. Mass of Object24.46 g Volume of Water12.5 mL Volume of Water and Object 16.3 mL

RULES FOR DETERMINING SIGNIFICANT FIGURES Rule #1: Nonzero digits always count as significant figures: Examples: 438 g_____ sig fig m_____ sig fig 1.7 cm_____ sig fig L_____ sig fig

Rule #2: Captive zeros always count as significant figures: Examples: 506 dm_____ sig fig 1005 mL_____ sig fig kg_____ sig fig cm_____ sig fig Rule #3: Leading zeros do not count as significant figures: Examples: 0.8 g_____ sig fig 0.06 g_____ sig fig L_____ sig fig

Rule #4: Trailing zeros are significant only if the number contains a decimal point: Examples: 60 g_____ sig fig 4830 km_____ sig fig 8.0 dm_____ sig fig 1.60 sec_____ sig fig L_____ sig fig kg_____ sig fig

RULES FOR ROUNDING NUMBERS If the digit immediately to the right of the last significant figure you want to retain is: Less than the last significant digit should stay the same. Example: Round m to 3 significant figures. –Since the 2 is less than 5, you should round to __________ m

5 or greater the last significant figure should increase by 1. Example: Round g to 3 significant figures. –Since 8 is greater than 5, you should round to __________ g

What Do You Think? 1)Determine the number of significant figures in each of the following: a d b e c. 6500f ) Round each of the following to 2 significant figures. a b c ) Explain how the measurement 6.2 cm is different from 6.20 cm.

CALCULATIONS WITH MEASUREMENTS Rule #1: Whenever you add or subtract measurements, your answer should have as many DECIMAL PLACES as the measurement with the LEAST number of DECIMAL PLACES. EXAMPLE: g g = g g

Rule#2: Whenever you multiply or divide measurements, your answer should have as many SIGNIFICANT FIGURES as the measurement with the LEAST number of SIGNIFICANT FIGURES. EXAMPLE: cm × 5.5 cm = cm cm 2

Its Your Turn! Perform the following calculations and record your answer to the correct number of digits. a – 6.49 = b x = c / =

Scientific Notation Short hand for writing very large or small numbers Two parts: Coefficient and Power of 10 A number between 1 and 10 (can include 1 but not 10). Exponent:  + exponent  - exponent

Practice Write the following numbers in scientific notation: 1. 41, ,007, ,000,000

One Minute Paper You have one minute to answer these two questions concerning significant figures and calculations with measurements. –What was the most important thing you learned? –What is still muddy?