Understand how units behave and combine algebraically. Know the 4 common prefixes and their numeric meanings.

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1 Add Important The Metric Sytem Page: 91 NGSS Standard: N/A The Metric Sytem MA Curriculum Framework (006): N/A AP Phyic 1 Learning Objective: N/A Knowledge/Undertanding: Skill: Undertand how unit behave and combine algebraically. Know the 4 common prefixe and their numeric meaning. Be able to decribe quantitie uing metric unit with & without prefixe. Language Objective: Undertand and correctly ue the term unit and prefix. Accurately decribe and apply the concept decribed in thi ection, uing appropriate academic language. Note: A unit i a pecifically defined meaurement. Unit decribe both the type of meaurement, and a bae amount. For example, 1 cm and 1 inch are both length. They are ued to meaure the ame dimenion, but the pecific amount are different. (In fact, 1 inch i exactly.54 cm.) Every meaurement i a number multiplied by it unit. In algebra, the term 3x mean 3 time x. Similarly, the ditance 75 m mean 75 time 1 meter. Both the number and it unit are neceary to decribe any meaurement. You alway need to write the unit. Saying that 1 i the ame a 1 g in phyic i a ridiculou a aying 1 i the ame a 1x in math. The metric ytem i a et of unit of meaurement that i baed on natural quantitie (on Earth) and power of 10.

2 Add Important The Metric Sytem Page: 9 The metric ytem ha 7 fundamental bae unit: meter (m): length kilogram (kg): ma (even though kilo i actually a prefix, ma i defined baed on the kilogram, not the gram) econd (): time Kelvin (K): temperature mole (mol): amount of ubtance ampere (A): electric current candela (cd): intenity of light Each of thee bae unit i defined in ome way that could be duplicated in a laboratory anywhere on Earth (except for the kilogram, which i defined by a phyical object that i locked in a vault in the village of Sevre, France). All other metric unit are combination of one or more of thee even. For example: Velocity (peed) i a change in ditance over a period of time, which would have unit of ditance/time (m/). Force i a ma ubjected to an acceleration. Acceleration ha unit of ditance/time (m/ ), and force ha unit of ma acceleration. In the metric ytem thi combination of unit (kg m/ ) i called a newton (ymbol N ), which mean: 1 N 1 kg m/ (The ymbol mean i identical to, wherea the ymbol = mean i equivalent to.)

3 Add Important The Metric Sytem Page: 93 The metric ytem ue prefixe to indicate multiplying a unit by a power of ten. There are prefixe for power of ten from to The mot commonly ued prefixe are: mega (M) = 10 6 = kilo (k) = 10 3 = centi (c) = 10 = = 0.01 milli (m) = 10 3 = 1 1,000 = micro (μ) = 10 6 = = Thee prefixe can be ued in combination with any metric unit, and they multiply jut like unit. 35 cm mean 35 time c time m or (35)( )(m). If you multiply thi out, you get 0.35 m. Any metric prefix i allowed with any metric unit. For example, tandard atmopheric preure i Pa. Thi ame number could be written a kpa or MPa. There i a popular geek joke baed on the ancient Greek heroine Helen of Troy. She wa aid to have been the mot beautiful woman in the world, and he wa an inpiration to the entire Trojan fleet. She wa decribed a having the face that launched a thouand hip. Therefore a millihelen mut be the amount of beauty required to launch one hip.

4 Add Important The Metric Sytem Page: 94 Converion If you need to convert from one prefix to another, the rule of thumb i that if the prefix get larger, then the number need to get maller and vice-vera. For example, uppoe we need to convert 0.5 mg to μg. The prefix m mean 10 3 and μ mean Therefore, you can replace the prefix m with the number 10 3, and the prefix μ with the number You can think of the rule in the following way: 0.5 mg = x μg (0.5) (0.001) g = (x) ( ) g (0.5)(0.001) 50 g x To do thi in your head uing common ene, you can realize that when you jump from milli to micro, the prefix i getting maller by 3 decimal place (going from 10 3 to 10 6 ), which mean the number that i attached to it need to get bigger by 3 decimal place in order to keep the combined number-and-prefix the ame. The anwer mut therefore be 50 μg.

5 Add Important The Metric Sytem Page: 95 The MKS v. cg Sytem Becaue phyic heavily involve unit that are derived from other unit, it i important that you make ure all quantitie are expreed in the appropriate unit before applying formula. (Thi i how we get around having to do factorlabel unit-cancelling converion like you learned in chemitry for every ingle phyic problem.) There are two meaurement ytem ued in phyic. In the MKS, or meterkilogram-econd ytem, unit are derived from the S.I. unit of meter, kilogram, econd, mole, Kelvin, ampere, and candela. In the cg, or centimeter-gram-econd ytem, unit are derived from the unit of centimeter, gram, econd, mole, Kelvin, ampere, and candela. The following table how ome example: Quantity MKS Unit S.I. Equivalent kg m force newton (N) cg Unit S.I. Equivalent g cm dyne (dyn) energy joule (J) kg m erg g cm magnetic flux denity tela (T) N, kg m A A gau (G) 0.1dyn 0.1 g cm, A A In thi cla, we will ue excluively MKS unit. Thi mean you only have to learn one et of derived unit. However, you can ee the importance, when you olve phyic problem, of making ure all of the quantitie are in MKS unit before you plug them into a formula! Homework Problem nm = m. 18.1m = μ J = k J kg = tonne