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1. PHY 205 Brad Armen Class web site: http://webspace.ship.edu/gbarmen/PHY205

2. Text: Physicsfor Scientists and Engineers … (9thed) By Serway and Jewett

3. HW: ‘WebAssign’: https://www.webassign.net Our course key: ship 1503 9518 (Adobe flash)

4. Submit Answer You get 5(?) tries, here’s how to use them wisely. Check math Bad Check thinking Bad Answer Still Wrong Get HELP!

5. CH.1 Review of some stuff: • Exponents and powers of ten representation: • Precision of physical quantities. • Error and the Sig Fig method. • Units of physical quantities.

6. Representing Numbers—Powers of 10 25 22 = (2×2×2×2×2) × (2×2) = 25+2 =27

7. Powers of ten are useful/standard:

8. Powers of ten are useful/standard:

9. Try this

10. Try this (12.×1030) = 1.2 × 1031 Standard

11. Try this

12. Try this (12.×10-20) = 1.2 × 10-19 Standard

13. Try this

14. Try this (0.75×1030) = 7.5 × 1029 Standard

15. Try this (300,000)+(4,000,000,000,000,000) = 4,000,000,000,300,000 = 4.0000000003 × 1015

16. Measuring things

17. Working precision: 1 mm (2 digits)

18. Working precision: 0.01 mm (3 digits)

19. Working precision: 0.00001 kW (5.5 digits)

20. Working precision: 0.000001 V (6.5 digits)

21. Uncertainty ? (Looks closer to 4.6)

22. How to report a measurement? Honest but cumbersome: (but Looks closer to 4.6) Easier to work with: Easier yet: “Sig. fig.” notation! Implied uncertainty is

23. Measurement accuracy Q: How accurate is my measurement? Is it the same as my precision?

24. A: No! Q: Which one’s correct? What can I do????

25. A: (certified) copies of standards …

26. Some industrial examples …

27. Some industrial examples …

28. My DMM …. Reading Accuracy: