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Chapter 1 Measurement and Units 1.01 Numbers and units 1.02 A system of units 1.03 Measuring length and time 1.04 Volume and density 1.05 Measuring volume and density 1.06 More about mass and velocity 1.01 Numbers and units 1.02 A system of units Introduction to Physics Physics is the study of natural phenomena and properties of matter. Light Waves Heat Force and motion Field of study in physics Electricity and electromagnetism Electronics Nuclear Physics 1.01 Numbers and units Physical quantities are quantities that can be measured. The value of the measurement consists of a numerical magnitude and a units. Physical Quantity Base Quantity Derived Quantity Base Quantities Base quantities are physical quantities that cannot be defined in term of others quantities. SI International System of Units The seven base quantities are Length Mass Temperature Time Electric current Amount of substance Luminous intensity Quantity Unit Symbol Length Meter m Mass Kilogram kg Time Second s Temperature Kelvin K Current Ampere A Amount of substance Luminous intensity Mole mol candela cd The five important base quantities: Base Quantity Symbol SI Unit Length l Metre Symbol of SI unit m Mass m Kilogram kg Time t Second s Temperature T Kelvin K Current I Ampere A • Derived quantities are physical quantities derived from combination of base quantities through multiplication or division or both multiplication and division. Prefixes are used to simplify the description of physical quantities that are either very big or very small. Prefix Symbol Value Tera T 1012 Giga G 109 Mega M 106 Kilo k 103 Hecto ha 102 Deca da 101 Deci d 10-1 Centi c 10-2 Milli m 10-3 Micro μ 10-6 Nano n 10-9 Pico p 10-12 Thanks God My Killer Husband Died During Christmas Makes Me Not Petrified Standard form or scientific notation is used to express magnitude in a simpler way. In scientific notation, a numerical magnitude can be written as: A x10n, where 1 ≤ A < 10 and n is an integer. Examples The distance between the Earth and the Sun = 150 000 000 000 m = 1.5 x 1011 m Example 1 1. 0.00000008 m ? m = 8 x 10-8 m 2. 75 000 000 kg ? kg = 7.5 x 107 kg 3. 0.0007766 m ? m = 7.766 x 10-4 m Example 2 1. 8 cm ? m = 8 x 10-2 m 2. 75 00 kg g = 7.5 x 103 x 103 g = 7.5 x 106 g 3. 0.776 mm ? m = 7.76 x 10-1 x 10-3 m = 7.76 x 10-4 m Exercise 1 Exercise 2 Exercise 3 Exercise 4 1. 0.03 m ? cm 2. 50 milliseconds ? Seconds 3. 94.6 MHz ? Hz 4. 1 000 000 mm ? km 5. 0.0005 Mg ? g

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