1. EGR 1011 September 7, 2010

2. EGR 1012 Today’s Agenda From last time: –Reports of Internet Search –Group Formation – Part I New Topics for today –Physical Quantities and Units –Unit Conversion –Homogeneity

3. EGR 1013 Fundamental, or Primary Quantities Those from which all others are derived –Physical Examples: –Electrical Examples:

4. EGR 1014 Derived, or Secondary Quantities Physical Examples: Electrical Examples:

5. EGR 1015 What Units Should We Use? Example distance units: Example time units:

6. EGR 1016 What Happens If We Mix Units? Consider the Mars Climate Orbiter that was launched in 1998. It turns out that someone at NASA forgot to convert English units (pounds) to metric units (Newtons) when calculating the necessary rocket thrust to put the craft in orbit around Mars Guess what happened?

7. EGR 1017 Standard We Will Use We will follow the International System of Units – also known as the SI standard –It includes: Distance measured in meters (m) Mass measured in kilograms (kg) Time measured in seconds (s) Charge measured in Coulombs (C) Temperature measured in degrees Kelvin ( o K or K) That means we’ll need to convert other measures to our standard

8. EGR 1018 Class Activity #1 a.) A tractor-trailer truck is traveling at 60 miles per hour eastbound on Interstate 195 towards the North Dartmouth exit. Determine the speed of the truck i.) in feet per second ii.) in meters per second iii.) in kilometers per hour. b.) What is the maximum legal speed in centimeters per hour in a 55 miles per hour posted speed zone?

9. EGR 1019 Homework for Thursday In the textbook, –Read Chapter I (Introduction) –Read Chapter 1 Visit the Science & Engineering Tutoring Center and find out what hours tutors are available for each of your IMPULSE math and engineering classes Turn in your schedule for this semester with the tutoring days and hours for each class.