1 / 14

Units and Conversions

Units and Conversions. What is. Ratio of an igloo’s circumference to its diameter? Eskimo π Time between slipping on a peel and smacking the pavement? 1 bannosecond 1000 aches? 1 killohurtz. Quantity (Q) = Numerical Value * Units (U)

kermit-ruiz
Download Presentation

Units and Conversions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Units and Conversions

  2. What is • Ratio of an igloo’s circumference to its diameter? • Eskimo π • Time between slipping on a peel and smacking the pavement? • 1 bannosecond • 1000 aches? • 1 killohurtz

  3. Quantity (Q) = Numerical Value * Units (U) Without the units to value has no meaning except as a ratio.

  4. Types of dimensions • Fundamental or base, what system is built on • Derived, the ones that are built on the base dimensions • For mechanical systems we have length, time, and mass or force as base

  5. SI System of Units (International System) • An absolute system (not gravity dependent) • Comes from the “metric system” or MKS • Base units: • Length: meter, m • Time: second, s • Mass: kilogram, kg Derived unit: Force, newton, N or kg m/s2

  6. SI System • Base units: • Length, meter • Time, second • Mass, kilogram • Electrical current, ampere • Temperature, kelvin • Amount of substance, mole • Luminous intensity, candela

  7. SI System • Supplemental Units: • Plane angle: radian, rad • Solid angle: steradian, sr • Derived Units: • See tables 6.4 and 6.5 on pg 207 • See figure 6.2 on pg 208 for relationships

  8. SI System • SI System is a base 10 system • Use prefix to identify size of unit • 109 giga G • 106 mega M • 103 kilo k • 10-3 milli m • 10-6 micro μ • 10-9 nano η

  9. Rules for Using SI Units • Look at section 6.6, pg 210 • Symbols and names • Multiplication and division • Numbers

  10. Engineering Notation • Scientific notation: number between 0 and 1.0 times 10 to a power, example 2.334 * 105m • Engineering notation: number between 0.1 and 1000 times 10 to a power of 3, 6, 9, -3, -6, -9, etc., example 233.4 km or 233.4 * 103 m

  11. Coherent and Noncoherent Systems Coherent systems: SI, US Customary No additional conversion factors needed Noncoherent systems: American Engineering System Additional conversion factor needed 1 lbf = 32.174 lbms2/ft

  12. US Customary System • Base units: • Length, foot, ft • Time, second, s • Force, pound, lb • Derived unit: • Mass, slug

  13. American Engineering System • Base units: • Length, ft • Time, s • Force, lbf • Derived unit: • Mass, lbm, 32.174 lbm = 1 slug

  14. Effect • For equation F = ma • SI system N = 1 kg m/s2 • USC system lb = 1 slug ft/s2 • Am Engr System lbf = 32.174 lbm ft/s2

More Related