CHAPTER 1: THE PHYSICS TOOL KIT Sections 1.1 and 1.2

The Physics Tool Kit: Ch1, Sections 1 and 2 Objectives  Explain the need for standardization of measurement.  Use the metric and English systems of measurement.

Introduction  The physics student must be able to:  Analyze a problem  Choose a correct concept formula  Manipulate an equation  This chapter gives the basic tools for a physics student.  Math techniques  Significant digits  Accuracy and precision  Problem solving strategy

1.1 Standards of Measure  Standard of measure – sets units of measurement for length, weight, and other quantities defined in a way that is useful to a large number of people.

 Some interesting historical measurement standards.  Chain – 100 links used for surveying = 66 ft  Rod – 16 men lined up foot to foot; now standardized to 16 1/2 feet  Yard – tip of king’s nose to fingertips of outstretched hand.  Foot – rod divided by 16; was also common to use length of one’s own foot.  Inch – was the length of three barely corns.

 US system, sometime called English system, of measurements is a combination of Anglo-Saxon, Roman, and French-Norman weights and measures.  In 1790’s, a decimal system based on the metric system was developed in France  Many nations began adopting as official measurement system.  By 1970, the US was the only non-metric industrialized nation.

Lost in Space

 Many businesses, industry and government agencies in the US have now converted voluntarily to the metric system.  In many industries, you – the student and worker – will need to know and use both.

1.2 Introduction to the Metric System  SI System of measurement is based on metric system  Gabriel Mouton ( )  System is based on factors of 10  Units are made bigger or smaller by using SI prefixes

SI Base Units Basic UnitSI AbbreviationQuantity Measured metermlength kilogramkgmass secondstime ampereAelectric current KelvinKtemperature candelacdlight intensity molemolamount

SI Derived Units Derived UnitAbbreviationQuantity Measured literL of lvolume cubic meterm3m3 volume square meterm2m2 area NewtonNforce meter per secondm/sspeed JouleJenergy wattWpower

SI Prefixes MultiplePower of 10PrefixPrefix Symbol teraT gigaG megaM kilok hectoh dekada (base) decid centic millim micro  nano  picop

SystemLengthTimeMassForce & Weight Englishfoot (ft)second (s)slugpound (lb) SImeter (m)second (s)kilogram (kg)Newton (N) 1 lb = 16 ounces (oz)1 kg weighs 9.80 N or 2.2 lb 1 lb = 4.45 N1 slug weighs 32.2 lb 1 kg = 1000 g1 slug = kg Comparison of English and SI Units Weight and Mass Conversions