1. 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

2. 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

3. 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.

4. 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.

5. 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

6. 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

7. How Many Sig Figs? 0.0027 g (a)4 (b)5 (c)3 (d)2

8. How Many Sig Figs? 9.6 x10 -1 kg (a)4 (b)5 (c)3 (d)2

9. How Many Sig Figs? 67421 J (a)4 (b)5 (c)3 (d)2

10. How Many Sig Figs? 67400 J (a)4 (b)5 (c)3 (d)2

11. How Many Sig Figs? 0.006070 °C (a)7 (b)3 (c)4 (d)6

12. How Many Sig Figs? 0.18 kg (a)4 (b)5 (c)3 (d)2

13. How Many Sig Figs? 12271 kg (a)4 (b)5 (c)3 (d)2

14. How Many Sig Figs? 744.00 m (a)4 (b)5 (c)3 (d)2

15. How Many Sig Figs? 2.60x10 -2 m (a)4 (b)5 (c)3 (d)2