Freshman Clinic 1:

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CHAPTER 6

• Freshman Clinic 1
• 4 DECEMBER 2006 Lecture Week 12
• ROWAN UNIVERSITY
• College of Engineering
• Dr Peter Mark Jansson, PP PE
• Associate Professor
• DEPARTMENT OF ELECTRICAL COMPUTER ENGINEERING
• Autumn Semester 2006

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Admin

• Returned Mid-Terms
• Class average 83
• HW 7 due today
• HW 8 due next week
• See me if you are missing work, many have missed
  assignments in 1-6

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Freshman Clinic I

• Todays Learning Objectives
• physical quantities
• dimensions
• units
• SI units and symbols
• rules for using and conversions

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Chapter 6 Dimensions, units and conversions

• Engineering Units
• SI
• Systeme International dUnites, a modification
  and refinement to the MKS (meter, kilogram,
  second) system. Is used internationally with
  little exception (optional in US)
• US Customary and Engineering Systems
• US foot, pound, second (slug for mass)
• Engineering foot, pound-force, second
  (pound-mass for mass)

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What is a physical quantity?

• Recognized only with respect to Units
• All quantities we measure are a numerical
  coefficient times an accepted unit of measure
• If we have a Length of 50 meters (this Length is
  our physical quantity) and the 50 is the
  coefficient with meters being the unit of measure
• Do not confuse the physical quantity with the
  dimension (i.e., length can me thought of in
  cubits, feet meters, inches, etc.)

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What are the key dimensions?

• Fundamental
• 1. Absolute System
• Length (L) Time (T) and Mass (M)
• 2. Gravitational System
• Length (L) Time (T) and Force (F)

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What are the key dimensions?

• Derived
• 1. Absolute System (some examples)
• Force MLT-2
• Velocity ML-1
• Energy ML2T-2
• see Table 6.1 (p. 204)

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What are the Key Units

• Seven base units in SI for you to remember
• Length meter (m)
• Time second (s)
• Mass kilogram (kg)
• Electric current ampere (A)
• Thermodynamic temperature kelvin (K)
• Amount of substance mole (mol)
• Luminous intensity candela (cd)

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Chapter 6 Other derived units

• Pages 207 208
• Tables 6.4 and 6.5
• IMPORTANT FIGURE 6.2

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General rules for use

• numerical value of any measurement should be
  recorded as a number between 0.1 and 1000
• pick appropriate prefix from Table 6.8
• Preferred prefixes include mega, kilo, milli,
  micro
• see exceptions that follow

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Three main exceptions

• preferred prefixes should be used except
• 1. when expressing area and volume
• hecto, deka, deci and centi are common
• 2. when discussing different values of same
  quantity in table or paper
• 3. sometimes a particular multiple is recommended
  and used consistently

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Read sections 6.6 6.8

• Lets review 6.6.1 6.6.3 together

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HW Assignment 8

• Due Monday, 4 December, 9.25 AM at Lecture
•  Intro. To Engineering Design and Problem
  Solving, pp. 221-225
• 6.2, 6.4, 6.10, 6.20, 6.28