CHAPTER 1 PHYSICS FOR JUNIOR HIGH SCHOOL VII

Something measurable  stated in number (quantitative), for instance: length, mass, time, temperature, etc. PHYSICS FOR JUNIOR HIGH SCHOOL VII QUANTITY MAIN QUANTITY DERIVED QUANTITY QUANTITY QUANTITY

MAIN QUANTITY PHYSICS FOR JUNIOR HIGH SCHOOL VII  Main quantity is a quantity that its unit is determined first, or a quantity that its unit is defined especially based on international conference.  There are 7 main quantities QuantityUnitUnit Symbol lengthMeterM MassKilogramKg TimeSecondS Electric currencyAmpereA TemperatureKelvinK Substance AmountMole Light IntensityCandelaCd

PHYSICS FOR JUNIOR HIGH SCHOOL VII DERIVED QUANTITY DD erived quantity is a quantity that can be derived or taken from main quantities DD erived quantities and their units QuantityUnitSymbol AreaAM2M2 VolumeVM3M3 VelocityVM/s or m.s –1 AccelerationAM/s 2 or m.s –2 ForceFKg.m/s 2 or kg.m.s –2 WorkWKg.m 2 /s 2 or kg.m 2.s –2 PowerPKg.m 2 /s 3 or kg.m 2.s –3

PHYSICS FOR JUNIOR HIGH SCHOOL VII THE INTERNATIONAL UNIT THE INTERNATIONAL UNIT  THE INTERNATIONAL UNIT OF LENGTH The unit of length is meter 1 meter = The space of two scratches on standard meter bar that is made of the compound of platinum-iridium. It is kept in the International Bureau of Weights and Measures (Sevres, Frances) on November in1983, the definition of meter standard was changed, it was determined that 1 meter is the travelled distance of light (in vacuum) in duration of 1/ second

PHYSICS FOR JUNIOR HIGH SCHOOL VII THE INTERNATIONAL UNIT THE INTERNATIONAL UNIT OF MASS The standard unit of mass is kilogram, which means the mass of a platinum-iridium cylinder that is kept in Bureau of Weights and Measures (Sevres, France). The international derived mass standard for U.S.A called prototype kilogram Number 20, kept in a dome in Bureau of National Standard The standard kilogram number 20 that is kept in the bureau of national standard of U.S.A is a platinum cylinder, kept under the two bell-shaped glass domes (Sources: Serway and Jewett, Physics for Scientists and Engineers, 6th edition, 2004)

PHYSICS FOR JUNIOR HIGH SCHOOL VII INTERNATIONAL UNIT IIIINTERNATIONAL UNIT OF TIME The standard for time is second (s). 1 second is defined as the duration that is needed by cesium atom-133 for vibrating times in transition between two energy level in its basic energy

PHYSICS FOR JUNIOR HIGH SCHOOL VII UNIT CONVERSION UNIT CONVERSION  UNIT CONVERTION OF LENGTH, MASS, AND TIME Unit Conversion of length and Mass 1.2,5 km =... m cm=... m g =... kg 4.4,25 g =... mg Example Convert the following units ! answer : 1.2,5 km = 2,5 × m= m cm = × 1/100 m= 15 m g = × 1/1.000 kg= 2 kg 4.4,25 g= 4,25 × mg= mg

PHYSICS FOR JUNIOR HIGH SCHOOL VII UNIT CONVERSION Unit conversion of time Example Convert the following units ! 1.1,5 hours=... minutes seconds=... minutes 1.1,5 hours= 1,5 × 60 minutes= 90 minutes seconds = 360 × 1/60 minutes = 6 minutes Answer : 1 hour = 60 minutes or 1 minute = 1/60 hour 1 minute = 60 seconds or 1 seconds = 1/60 minute 1 hour = seconds or 1 second = 1/3.600 hour

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