Dimensional Analysis Chapter 2 Systems of Units Section

Systems of Units Section 2. 3 Unit Abbreviation Mass Kilogram Gram (CGS) kg Length

Derived Units Quantity Unit Symbol Equivalent in Terms of Base Units Volume liter L

Section 2. 2 Dimensional Analysis �Utilizes conversion factors in order to convert between units

Example � How many centimeters are in 1. 39 feet? Hint: 1 in =

Conversions Involving More than One Unit The speed of sound in air at sea

Conversions Involving Cubed Units � Express a density of 8. 4 g/cm 3 in

Combination Carry out the following conversion: 0. 04 g/min ∙ m 3 to lbm/hr

For Super Duper Fun In 1916 Nusselt derived a theoretical relation for predicting the

Assignments �Complete the following questions at the end of Chapter 2: � 2. 1,

Slides: 10

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Dimensional Analysis Chapter 2

Systems of Units Section 2. 3 Unit Abbreviation Mass Kilogram Gram (CGS) kg Length Meter Centimeter (CGS) m Time Second s Temperature Kelvin K Amount of substance Mole mol Electric Current Ampere A Luminous intensity Candela cd Physical Quantity

Derived Units Quantity Unit Symbol Equivalent in Terms of Base Units Volume liter L 0. 001 m 3 1000 cm 3 Force newton (SI) dyne (CGS) N 1 kg ∙ m/s 2 1 g ∙ cm/s 2 Pressure pascal (SI) Pa 1 N/m 2 Energy, work joule (SI) erg (CGS) gram-calorie J cal 1 N ∙ m = 1 kg ∙ m 2/s 2 1 dyne∙cm = 1 g∙cm 2/s 2 4. 184 J = 4. 184 kg ∙ m 2/s 2 watt W 1 J/s = 1 kg ∙ m 2/s 2 Power

Section 2. 2 Dimensional Analysis �Utilizes conversion factors in order to convert between units of one thing to units of something else • Examples of conversion factors: � 1 foot = 12 inches � 2. 54 cm = 1 inch

Example � How many centimeters are in 1. 39 feet? Hint: 1 in = 2. 54 cm See Sample Exercise 1. 9 (Pg. 25) � 42. 4 cm

Conversions Involving More than One Unit The speed of sound in air at sea level is 340 m/s. Express this speed in miles per hour. � Hint: 1 mile = 1. 6093 km � � See Sample Exercise 1. 10 (Pg. 26) and Useful Conversion Factors and Relationships (Inside back cover) � 760 mile/hr

Conversions Involving Cubed Units � Express a density of 8. 4 g/cm 3 in terms of SI base units (kg/m 3). See Sample Exercise 1. 11 (pg. 27 -28) 8400 kg/m 3 OR 8. 4 x 103 kg/m 3

Combination Carry out the following conversion: 0. 04 g/min ∙ m 3 to lbm/hr ∙ ft 3 1. 5 x 10 -4 lbm/hr ∙ ft 3

For Super Duper Fun In 1916 Nusselt derived a theoretical relation for predicting the coefficient of heat transfer between a pure saturated vapor and a colder surface: where h = mean heat transfer coefficient, Btu/(hr)(ft 2)( ºF) k = thermal conductivity, Btu/(hr)(ft)( ºF) = density, lb/ft 3 g = acceleration of gravity, 4. 17 x 108 ft/(hr)2 = enthalpy change, Btu/lb L = length of tube, ft = viscosity, lbm/(hr)(ft) T= temperature difference, ºF What are the units of the constant, 0. 943?

Assignments �Complete the following questions at the end of Chapter 2: � 2. 1, 2. 2, 2. 6, 2. 8, 2. 11