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Bellwork

Bellwork. On the left side of your notebook, write the measurements using the desired metric prefix: 2,400 gm = ______ kg 4 L = ______ mL 660 nm = __________ m 9.8 s = __________ ps. Physics. 9/13/13. What’s up today? Metric System Practice (if needed) Dimensional Analysis

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Bellwork

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  1. Bellwork • On the left side of your notebook, write the measurements using the desired metric prefix: • 2,400 gm = ______ kg • 4 L = ______ mL • 660 nm = __________ m • 9.8 s = __________ ps

  2. Physics 9/13/13 • What’s up today? • Metric System Practice (if needed) • Dimensional Analysis • How Many Light-years is your Pencil?

  3. Metric System • 5.42x106 m = ________ Mm • 4.20x10-5 m = ________ μm • 2.1x10-10 m = ________ nm = _________ fm

  4. Dimensional Analysis • Physicists don’t just add numbers…as wonderful and fascinating as they are. • How do we do math with units?

  5. Arithmetic • Rule 1: We can only add or subtract same units. Not okay: 20 kg + 300 m = ???

  6. Arithmetic • Rule 2: Multiplying or dividing with units results in…wait for it…

  7. Arithmetic • Rule 2: Multiplying or dividing with units results in…wait for it…multiplying or dividing with units. ]

  8. Arithmetic • Rule 3: Squaring or taking a root of a unit results in….

  9. Arithmetic • Rule 3: Squaring or taking a root of a unit results in….squaring or taking a root of a unit.

  10. Arithmetic • Rule 4: We cannot have a unit in the argument of an exponential, log, or trig function.

  11. Unit Conversion • How to convert from one unit to another?

  12. Unit Conversion • How to convert from one unit to another? • Chaining! • Go from m to cm to mm:

  13. Unit Conversion • Chemistry:

  14. Your turn. • Rest of class: activity time. • Read instructions, perform measurements in small groups. • If an instrument is being used, skip and come back. • Ask Mr. Abbott for help!!!!!

  15. Scientific Notation • In physics, we use some very BIGand some very small numbers. • Charge of an electron: .000000000000000001602 C • Distance to the Sun: 149,700,000,000 m

  16. Scientific Notation • There has to be a better way!

  17. Scientific Notation • There has to be a better way! • Scientific notation. • Taking advantage of the “powers” of powers of ten…

  18. Scientific Notation • Easy example: • Write 2,000 in scientific notation. • Easy-ish: • Write 20,200 in scientific notation. • Not-quite-as-easy: • 299,800,000 • Tough-ish: • 0.00000913

  19. Scientific Notation • Want more detail? • Base-ten number system: ANY number in the system can be represented by adding multiples of powers of ten: 22,531 • Base-two number system: binary code. 001101

  20. Scientific Notation • Convenience of base-ten? • Can ALSO represent any number as a number b/w 1 and 10 multiplied by some power of ten:

  21. Metric System • The metric system takes advantage of powers of ten to make it easier to express units. • Every power of ten (103, 106, 10-3) has it’s own prefix (kilo, mega, milli).

  22. Metric System • The metric system takes advantage of powers of ten to make it easier to express units. • Every power of ten (103, 106, 10-3) has it’s own prefix (kilo, mega, milli). • Activity time!

  23. Next time… • Dimensional analysis. • How many lightyears long is a pencil?

  24. Roadmap: • After dimensional analysis, we move into basic math (functions and graphing). • THEN we start talking MOTION! Huzzah!

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