Phys 110 Dr Mymona Abutalib Tel 0505622285 mabutalibkau

Phys 110 Dr Mymona Abutalib Tel: 0505622285 mabutalib@kau. edu. sa Office hours: S-M-W 9 -11 am Coordinator Dr najlaa alharbi najlaa 24@hotmail. com Read the book Think! Ask questions Attendthe tutorials Informationis key No pain no gain ☺

Objectives After this lecture you should be able to… Differentiate Between base and derived quantities Explain Standards of measurements Define The International system of units Convert Units using the chain-link method Apply The scientific notation to numbers

Physical Quantities Physics is based on measurement of Physical Quantities. For example: length, time, mass, temperature, pressure. Physical Quantities Base quantities be independent of each other. Assumedto Length, mass and time. Derived quantities Defined in terms of base quantitiesvia equations. Velocity = Length Time

Derived SI Units (examples) Quantity unit Symbol Volume cubic meter m 3 Density Speed kilograms per kg/m 3 cubic meter per second m/s Newton kg m/ s 2 N Energy Joule (kg m 2/s 2) J Pressure Pascal (kg/(ms 2) Pa

Math and Units • Math- the language of Physics • SI Units – International System – MKS • Meter m • Mass kg • Time s • National Bureau of Standards • Prefixes

1. 3 The International System of Unit To express a very large and very small quantity we use : Power of ten Scientific Notation Exponent of ten 653000 m = 6. 53 E 8 m 0. 000 00729 s = 7. 29 E -6 s

Other Examples: • 5. 45 E+6 • 5. 45 x 10^6 or

Numbers less than 1 will have a negative exponent. A millionth of a second is: 0. 000001 sec 1. 0 E-6 1 x 10 -6 1. 0^-6

Prefixes of Units When we dealing with very large or very small measurements we use the prefixes. 101 102 103 106 109 nano micro milli centi desi n μ m c d Exp. 2. 67 x 109 watt = deka hecto da h kilo mega giga k M G 3. 21 x 10 -6 s =

1 -4 Changing Units We often need to change the units in the physical quantity by a method called chain link conversion In this method we multiply the original measurement by a conversion factor. Conversion factor: factor is a ratio of units that is equal to unity. Example 1 -Convert 2 min to seconds 60 s 2 min x ------- = 120 s 1 min 2 -Convert 4 kg to grams