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Physics Tool Kit Units (S.I. System - Meters, Kg, S) Unit Conversion Scientific Notation Accuracy and Precision Significant Figures Dimensional Analysis (Unit Analysis) Making Estimates
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Physics Tool Kit Units (S.I. System - Meters, Kg, S) Unit Conversion Scientific Notation Accuracy and Precision Significant Figures Dimensional Analysis (Unit Analysis) Making Estimates
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What is a significant figure? There are 2 kinds of numbers: –Exact: the amount of money in your account. Known with certainty. Approximate: weight, height—anything MEASURED. No measurement is perfect.
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Sig Figs and Measurement Significant Figures help us keep track of the precision of our measurements. The number of significant figures in a measurement is the number of digits actually measured plus one estimated digit. Example: Our ruler has divisions every centimeter and tenth of a centimeter. We can estimate to the hundredth of a centimeter. If we measure 24.28 cm we have four significant figures. If we measure 8.71 cm we have three significant figures.
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How Many Significant Figures? Nonzero digits are always significant Zeros between nonzero digits are significant Example: 20.3 m has three sig figs 1.0025 m has five sig figs
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How Many Significant Figures? Zeros at the end of a number and to the right of a decimal point are significant. Example: 62.100 g has five sig figs 2.000 000 kg has seven sig figs This is how we show that the measurement was made with precision – the values in those places just happened to be zero. (But we measured them to be zero.) Zeros used as placeholders are not significant Example: 15,000,000 years has two sig figs 0.006 kg has one sig fig (we could also say 6 g) WHY? Because we could just change units to get rid of the ‘placeholder’ zeros. Example: 6 g instead of 0.006 kg
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How Many Sig Figs? 0.0027 g (a)4 (b)5 (c)3 (d)2
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How Many Sig Figs? 9.6 x10 -1 kg (a)4 (b)5 (c)3 (d)2
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How Many Sig Figs? 67421 J (a)4 (b)5 (c)3 (d)2
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How Many Sig Figs? 67400 J (a)4 (b)5 (c)3 (d)2
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How Many Sig Figs? 0.006070 °C (a)7 (b)3 (c)4 (d)6
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How Many Sig Figs? 0.18 kg (a)4 (b)5 (c)3 (d)2
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How Many Sig Figs? 12271 kg (a)4 (b)5 (c)3 (d)2
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How Many Sig Figs? 744.00 m (a)4 (b)5 (c)3 (d)2
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How Many Sig Figs? 2.60x10 -2 m (a)4 (b)5 (c)3 (d)2
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