CHAPTER 1: THE PHYSICS TOOL KITSections 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. http://en.wikipedia.org/wiki/Pottle 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 http://www.cnn.com/TECH/space/9909/30/mars.metric/

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 (1618-1694) System is based on factors of 10

Units are made bigger or smaller by using SI prefixes

SI Base Units

Basic Unit SI Abbreviation Quantity Measured

meter m lengthkilogram kg masssecond s timeampere A electric currentKelvin K temperaturecandela cd light intensitymole mol amount

SI Derived Units

Derived Unit Abbreviation Quantity Measured

liter L of l volumecubic meter m3 volumesquare meter m2 areaNewton N forcemeter per second m/s speedJoule J energywatt W power

SI PrefixesMultiple Power of 10 Prefix Prefix

Symbol1 000 000 000 000

1012 tera T

1 000 000 000 109 giga G1 000 000 106 mega M1000 103 kilo k100 102 hecto h10 101 deka da1 100 (base) - 0.1 10-1 deci d0.01 10-2 centi c0.001 10-3 milli m0.000 001 10-6 micro

0.000 000 001 10-9 nano

0.000 000 000 001

10-12 pico p

System Length Time Mass Force & Weight

English foot (ft) second (s)

slug pound (lb)

SI meter (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 N 1 slug weighs 32.2 lb1 kg = 1000 g 1 slug = 14.59 kg

Comparison of English and SI Units

Weight and Mass Conversions