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# P2Week1 - P2 Week 1 Significant figures Word problems 1...

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1 P2 Week 1 Significant figures, Word problems 1 Signifcant fgures Significant figures keep track of how precise a measured (or estimated) quantity is How many significant figures does 0.0012 have? Answer is 2. Don’t count the zeros before the first non-zero digit. Count all other digits. How many significant figures does 0.00102 have? A : 1 B : 6 C : 7 D : 2 E : 3 2

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2 Signifcant fgures Is 0.00120 different from 0.0012 in any way? YES! By writing 0.00120 you are asserting that the digit after 2 is zero . So 0.00120 is accurate to one more decimal point than 0.0012 Number of significant figures in 0.00120 is 3 while the number of significant figures in 0.0012 is 2. But what do you do if there is no decimal point? Example, how many significant figures does 10 have? Or 11? A way to avoid this confusion is to use scientific notation . 3 Scientifc notation Scientific notation is written in base 10. It has a coefficient and an exponent . 0.0012 is written as 1.2 x 10 -3 when SCIENTIFIC notation is adopted. 1.2 is the coefficient . -3 is the exponent. Rules: One digit before decimal point. The digit before decimal point cannot be 0 In other words, coefficient must be greater than or equal to 1 and less than 10. As many digits after decimal point as required. The number of significant figures is the total number of digits (including zeros) in the coefficient . 4
3 Scientifc notation problem How would you express 0.0234 in scientific notation correctly? A : 0.234 × 10 -1 B : 0.0234 × 10 0 C : 2.34 × 10 -2 D : 2.34 × 10 -1 E : 23.4 × 10 -3 5 Scientifc notation problem How would you express 0.0234 in scientific notation correctly? C : 2.34 × 10 -2 6

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4 Signifcant fgures and Formulae In the formula v=u+a t^2 / 2, you should take the 2 as known to infinite precision -- it plays no role in setting the significant figures of your answer. 7 Signifcant fgures and addition Practical Rule for addition and subtraction : Supply answer to the smallest number of decimal places from among the numbers involved in the calculation, rounding up if necessary. Example 1: 0.0012 + 0.0992 = 0.1004 Example 3: 0.012 - 0.0998 = - 0.088 Keep answer to 3 decimal places Example 2: 0.00120 + 0.0992 = 0.1004 Keep answer to 4 decimal places. Keep the answer as is (all numbers known to 4 decimal places). 8
5 Sig Fig problem 1 You add 1.234 to 0.01 in your exam. The calculator will give 1.244. You should express the answer as A : 1.244 B : 1.24 C : 1.25 D : 1.2 E : 1 9 Sig Fig problem 2 You add 1.235 to 0.01 in you exam. The calculator will give 1.245. You should express the answer as A : 1.245 B : 1.24 C : 1.25 D : 1.2 E : 1 10

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6 Sig Fig problem 3 You subtract 0.010 from 1.255 in you exam. The calculator will give 1.245. You should
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P2Week1 - P2 Week 1 Significant figures Word problems 1...

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