# Physical Quantities and Units - UMass D

Remainder of Todays Agenda Primary and Secondary Physical Quantities and Units Unit Conversion 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 well need to convert other measures to our standard Fundamental or Primary Quantities 7 SI base units: those from which all others are derived

meter kilogram second ampere kelvin candela mole (m) (kg) (s) (A) (K)

(cd) (mol) length weight time current temperature luminosity molecular quantity Quick in-class exercise: Identify physical examples, and electrical examples Derived or Secondary Quantities SI derived unit: derived from base units Unlimited number of derived units! Some examples:

meter / second meter / second squared newton pascal joule volt watt ohm farad henry hertz

(N) (Pa) (J) (V) (W) ()) (F) (H) (Hz) m/s m/s2 kgm / s2 N / m2 Nm kgmm2ms3mA1 J/s V/A C/V Vms / A 1/s

velocity acceleration force pressure energy voltage power resistance capacitance inductance frequency Commonly used prefixes T G M k tera giga

mega kilo 1012 109 106 103 d c d n p deci centi milli micro nano pico

10-1 10-2 10-3 10-6 10-9 10-12 What Units Should We Use? Example distance units: Example time units: What Happens If We Mix Units? Consider the Mars Climate Orbiter that was launched in 1998 (see handout). 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? 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? Homework for next class In the textbook, Read Chapter I (Introduction) Read Chapter 1

## Recently Viewed Presentations

• Configuration dependent, but 100Mbps is not too difficult for Snort to manage Flexibility made Snort the platform of choice for a number of applications in the R&D space Govt and University researchers frequently use Snort as a rapid prototyping platform...
• Recognize and explain the meaning of common idioms, adages, and proverbs. c. Demonstrate understanding of words by relating them to their opposites (antonyms) and to words with similar but not identical meanings (synonyms).
• Analyse the ways conflicting perspectives generate diverse and provocative insights.In your response, make detailed reference to your prescribed text and at least ONE other related text of your own choosing. 2008: Compare how the texts you have studied emphasise the...
• Native American Experience1200 BC - 1600. Characteristics of Native American Literature. Oral Tradition. Held a Moral Message. Used Animals and Nature Interchangeably. Believed in the Power of the Metaphor. Explained the un-explainable. Creation of the world. Where humans came from....
• Big Question: How can knowing another language create understanding? Monday. Tuesday. Wednesday. Thursday. ... jen and me made a copy of one line of hieroglyphs, it took a long time ... You can use Greek and Latin roots to help...
• Il y eu de nombreuses autres expositions par la suite, dans le monde entier : Nous pouvons citer « CyberneticSerendipity » (hasards cybernétiques heureux) qui s'est déroulée à l'Institut of Contemporary Art de Londres en 1968 et qui a réunit...
• 1st Angel. 2nd Angel. 3rd Angel. 4th Angel. 5th Angel. 6th Angel. 7th Angel. Sores. Sea to Blood. Heat. Darkens . Armageddon. Hail, Thunder, Lightning ... Well, the flow has become a flood and soon will be a torrent. It...
• If, however, we try to get readers to agree with us simply by impressing them with a famous name or by appealing to a supposed authority who really isn't much of an expert, we commit the fallacy of appeal to...