# Appendix – Useful numbers and conversions

CONTENTS

A1 Introduction A.1 Introduction

Quantitative analysis needs numbers. Many of those needed to understand and quantify eco-aspects of material production and use are presented in the Chapters of the text.

■ Table 2.1: approximate efficiency factors for energy conversion and the associated CO2 emission per useful MJ.

■ Table 6.5: the energy content of fossil fuels and the CO2 they emit when burnt.

■ Table 6.6: the energy efficiency of electricity generation and the related CO2 per useful kWhr.

■ Table 6.7: the energy and CO2 costs of alternative modes of transport.

■ Table 9.6: the energy and CO2 rating of cars as a function of mass.

■ Chapter 12: data sheets listing the attributes of 47 of the most widely used materials.

This appendix assembles further useful numbers and conversion factors.

A.2 Physical constants in SI units

 Physical constant Value in SI units Absolute zero temperature -273.2 °C Acceleration due to gravity, g 9.807 m/s2 Avogadro’s number, NA 6.022 X 1023 – Base of natural logarithms, e 2.718 – Boltzmann’s constant, k 1.381 X 10-23 J/K Faraday’s constant k 9.648 X 104 C/mol Gas constant, R 8.314 J/mol/K

 Physical constant Value in SI units Permeability of vacuum, p,0 1.257 X 10-6 H/m Permittivity of vacuum, e0 8.854 X 10~12 F/m Planck’s constant, h 6.626 X 10~34 J/s Velocity of light in vacuum, c 2.998 X 108 m/s Volume of perfect gas at STP 22.41 X 10~3 m3/mol

A.3 Conversion of units, general

 Quantity Imperial unit SI unit Angle, 6 1 rad 57.30° Density, p 1 lb/ft3 16.03 kg/m3 Diffusion coefficient, D 1 cm3/s 1.0 X 10~4 m2/s Energy, U See Section A5 Force, F 1 kgf 9.807 N 1 lbf 4.448 N 1 dyne 1.0 X 10~5 N Length, l 1 ft 304.8 mm 1 inch 25.40 mm 1 A 0.1 nm Mass, M 1 tonne 1000 kg 1 short ton 908 kg 1 long ton 1107 kg 1 lb mass 0.454 kg Power, P See Section A5 Stress, a See Section A4 Specific heat, Cp 1 cal/gal.°C 4.188 kJ/kg.°C Btu/lb.°F 4.187 kg/kg.°C Stress intensity, K1c 1 ksi Vin 1.10 MN/m3/2 Surface energy y 1 erg/cm2 1 mJ/m2 Temperature, T 1°F 0.556°K Thermal conductivity 1 cal/s. cm.°C 418.8 W/m.°C 1 Btu/h. ft. F 1.731 W/m.°C Volume, V 1 Imperial gall 4.546 X 10~3 m3 1 US gall 3.785 X 10~3 m3 Viscosity, n 1 poise 0.1 N. s/m2 1 lb ft. s 0.1517 N. s/m2