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PPMF101 – Lecture 1PPMF101 – Lecture 1

MeasurementMeasurement

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Basic quantity & Derived quantityBasic quantity & Derived quantity Base quantityBase quantity A quantity which is A quantity which is notnot

a combination of other a combination of other physical quantities.physical quantities.

Must be defined in Must be defined in terms of a standard.terms of a standard.

Length, mass, time, Length, mass, time, temperature, electric temperature, electric current, amount of current, amount of substance and substance and luminous intensityluminous intensity

Derived quantityDerived quantity A quantity which is a A quantity which is a

combination of two or combination of two or more physical more physical quantities.quantities.

Eg. Area, volume, Eg. Area, volume, velocity, acceleration, velocity, acceleration, density, work, energy density, work, energy and pressure.and pressure.

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1 meter1 meter The meter is the length of the The meter is the length of the

path traveled by light in path traveled by light in vacuum during a time interval vacuum during a time interval of 1/299,792,458 of a of 1/299,792,458 of a second.second.

1 meter is defined in terms of 1 meter is defined in terms of the distance traveled by light the distance traveled by light in vacuum. Velocity of light in in vacuum. Velocity of light in vacuum is important in this vacuum is important in this definition.definition.

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1 kilogram1 kilogram

A particular platinum-A particular platinum-iridium cylinder kept iridium cylinder kept at the International at the International Bureau of Weights Bureau of Weights and Measures near and Measures near Paris.Paris.

1 kilogram is defined 1 kilogram is defined by the mass of a by the mass of a particular platinum-particular platinum-iridium cylinder.iridium cylinder.

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1 second1 second One second is One second is

defined as the time defined as the time required for required for 9,192,631,770 9,192,631,770 periods of radiation periods of radiation emitted by cesium emitted by cesium atoms. atoms.

1 second is defined 1 second is defined in terms of periods in terms of periods of radiation of of radiation of cesium atom.cesium atom.

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Importance of unit conversionImportance of unit conversion

Scientific purposesScientific purposes Trades and commerceTrades and commerce Daily transactionDaily transaction

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Wrong conversion can lead to Wrong conversion can lead to disasterdisaster

NASA Mars Climate OrbiterNASA Mars Climate Orbiter "The "The 'root cause''root cause' of the loss of the of the loss of the

spacecraft was the spacecraft was the failed failed translation of translation of English units into metric unitsEnglish units into metric units in a in a segment of ground-based, navigation-segment of ground-based, navigation-related mission softwarerelated mission software, as NASA has , as NASA has previously announced," said Arthur previously announced," said Arthur Stephenson, chairman of the Mars Climate Stephenson, chairman of the Mars Climate Orbiter Mission Failure Investigation Board.Orbiter Mission Failure Investigation Board.

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Wrong conversion can lead to Wrong conversion can lead to disasterdisaster

September 30, 1999September 30, 1999 NASA NASA lost a 125 million Mars orbiter lost a 125 million Mars orbiter

because a Lockheed Martin engineering because a Lockheed Martin engineering team used English units of measurement team used English units of measurement while the agency’s team used the more while the agency’s team used the more conventional metric system for a key conventional metric system for a key spacecraft operation – CNN.spacecraft operation – CNN.

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Wrong conversion can almost lead to Wrong conversion can almost lead to disasterdisaster

The The Gimli GliderGimli Glider is the nickname of the is the nickname of the Air Canada aircraft that was involved in a aircraft that was involved in a notable notable aviation incident. incident.

On 23 July 1983, On 23 July 1983, Air Canada Flight 143Air Canada Flight 143, , a a Boeing 767-200 jet, ran out of fuel at jet, ran out of fuel at 26,000 feet (7,920 m) altitude26,000 feet (7,920 m) altitude, about , about halfway through its flight from halfway through its flight from Montreal to to Edmonton via Ottawa. Edmonton via Ottawa.

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The crew was able to glide the aircraft The crew was able to glide the aircraft safely to an emergency landing at Gimli safely to an emergency landing at Gimli Industrial Park Airport, a former Canadian Industrial Park Airport, a former Canadian Air Force base at Gimli, Manitoba.Air Force base at Gimli, Manitoba.

The incident was partly due to The incident was partly due to miscalculation in fuel reloading using miscalculation in fuel reloading using metric system metric system in place of the British in place of the British system.system.

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Effective technique of Unit Effective technique of Unit ConversionConversion

1.1. Write the unit in traditional form and not the Write the unit in traditional form and not the index form.index form.

eg. eg.

2.2. Remember or look up the conversion factor.Remember or look up the conversion factor.3.3. Multiply the initial quantity with the proper Multiply the initial quantity with the proper

conversion factor so that only the required conversion factor so that only the required units are left, the others cancelled off.units are left, the others cancelled off.

1msnotands

m

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Conversion factor to rememberConversion factor to remember

1 km 1 km = = 1000 m1000 m 1 m1 m == 100 cm100 cm 1 cm1 cm= = 10 mm10 mm 1 kg1 kg = = 1000 g1000 g 1 h1 h == 60 min60 min 1 min1 min == 6060 ss 1 h1 h == 3600 s3600 s Remember the values for the prefixes.Remember the values for the prefixes. The rest – look up the conversion tableThe rest – look up the conversion table

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Unit ConversionUnit Conversion ConvertConvert (a)(a) 110 km/h to m/s110 km/h to m/s (b) 340 m/s to km/h(b) 340 m/s to km/h (c) 300 m(c) 300 m22 to cm to cm22

(d) 20 m(d) 20 m33 to cm to cm33

(e) 1000 kg/m(e) 1000 kg/m33

(f) 15 nm to m(f) 15 nm to m (g) 25 A to (g) 25 A to AA (h) 12 MW to kW(h) 12 MW to kW