Presentation on theme: "Significant Figures Every measurement has a limit on its accuracy based on the properties of the instrument used. we must indicate the precision of the."— Presentation transcript:
1 Significant FiguresEvery measurement has a limit on its accuracy based on the properties of the instrument used.we must indicate the precision of the measurement by using the correct number of significant figuresPrecision – the consistency of a measurement, how repeatable it is
3 Check your answer with the person next to you Object A, measured with Ruler I should be recorded as ________ but as measured with Ruler II should be recorded as _________Check your answer with the person next to you
4 Check your answer with the person next to you Object B, measured with Ruler I is _______________Object B, measured with Ruler II is _______________Check your answer with the person next to you
5 Which ruler is the most precise? Which ruler is the least accurate?
6 What happens if an object is directly on the 3 of the ruler What happens if an object is directly on the 3 of the ruler? What decimal place to record?
7 Check your answer with the person next to you what is its smallest division? _________How should measurements using Ruler IV be recorded (to how many decimal places)? ________Check your answer with the person next to you
8 Rules for SigFigs Nonzero digits are ALWAYS significant Zeroes are only sometimes significant…All final zeroes after a decimal point are significantZeroes between two other significant digits are always significantZeroes used soley as placeholders are NOT significantZeroes between a decimal point and a nonzero digit are NOT significant.
9 Some examplesm s m $18,000 $18,000.00 $18,000. cm
10 1. Give the number of sig. fig 1. Give the number of sig. fig. and the number of decimal places in each of the number below. a) b) c) d) e) 3,000 f) 3,000. g) 3,000.00
11 # of sig. fig.# of decimal placesa) 72.3242b)53c) 0.0031d)e) 3,000assume 1f) 3,000.g) 3,000.006
12 2. These numbers have ambiguous zeroes 2. These numbers have ambiguous zeroes. Remove the ambiguity by expressing them in scientific notation. a) in 2 sig. fig. b) in 3 sig. fig. c) in 4 sig. fig. d) 2100 in 3 sig. fig. e) 790,000 in 4 sig. fig. f) 3800 x 10-7 in 3 sig. fig.
13 Answersa) in 2 sig. fig.4.2 x104b) in 3 sig. fig.4.20 x 104c) in 4 sig. fig.4.200 x 104d) 2100 in 3 sig. fig.2.10 x 103e) 790,000 in 4 sig. fig.7.900 x 105f) 3800 x 10-7 in 3 sig.fig.3.80 x 10-4
14 When you perform any arithmetic operation, it is important to remember that the result can never be more precise than the least precise measurement.
15 Adding and Subtracting To add or subtract measurements, first perform the operation, then round off the result to correspond to the least precise value involved. For example, add these values:m m m = m 3.21mLeast precise measurement? ______Round answer to _______30.24m
16 Multiply and DivideAfter performing the calculation, note the factor that has the least number of significant digits. Round the product or quotient to this number of digits. For example, multiply3.22 cm by 2.1 cm = cm2 corrected to _________6.8 cm2
17 36.5 m divided by 3.414 s = 10.691 m/s corrected to ________ Divide these two measurements and report answer with correct number of significant digits36.5 m divided by s = m/s corrected to ________10.7 m/s
18 Let’s review… Some Practice problems 1) 2804m 2) 2.84km 3)0.029m 4) m 5) 4.6x105m 6) 4.06x105m 7) 750m 8) 75m 9)75,000 m 10) 75,000. m 11) 75,000.0m 12) 10 cm
19 Answers Some Practice problems 1) 2804m 2) 2.84km 3)0.029m 4) m 5) 4.6x105m 6) 4.06x105m 7) 750m 8) 75m 9)75,000 m 10) 75,000. m 11) 75,000.0m 12) 10 cm
20 More practice! 1) 6.201 cm + 7.4 cm + 0.68 cm + 12.0 cm = ? 2) 1.6 km + 1.62 m + 1200 cm = ?3) g - 7.8 g = ?4) m - 6.0 m = ?5) m + kg = ?6) 131 cm x 2.3 cm = ?7) m x m = ?8) 20.2 cm divided by 7.41 s = ?9) g divided by ml = ?