Introductory Unit

SI Units System International 

• There are many types of units which are used to measure all types of quantities. Perhaps you know your weight in pounds, but would you know it in stone? A stone is one of a plethora of units used historically. (and still currently in some countries) Find out how much the unit "stone" is using this link http://www.unc.edu/~rowlett/units/index.html
• To standardize the units used to measure things an international agreement was made to use SI or System International. This system is accepted as standard in physics (and science) and will be the fundamental system of measurement for this course.
  • base units / derived units - http://physics.nist.gov/Document/SIDiagramBW.pdf or http://physics.nist.gov/Document/SIDiagramColor.pdf (in colour)
    • identify which base and derived units we will use in this course
  • defining base units; meter, second, kilogram - http://www.unc.edu/~rowlett/units/index.html
  • SI prefixes - http://www.unc.edu/~rowlett/units/prefixes.html

Scientific Notation

• see p565 in 'Physics 11' text
• http://www.nyu.edu/pages/mathmol/textbook/scinot.html

Unit Conversion

• McCulloch method of converting any units (relates to dimensional analysis p571 in text)
  • creating 1 from any equality
  • you can multiply anything by 1 without changing it
  • treat units as algebraic variables
• check your conversions using the web
  • http://www.onlineconversion.com/

Length / Distance Scale

• estimating order of magnitude for some examples
• http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html

Significant Digits

• rules
  • see text p566
  • see the rules in this link (better than text to describe issue of zero's)- http://www.physics.uoguelph.ca/tutorials/sig_fig/SIG_dig.htm
• simple arithmetic - see link above
  • multiplication / division
  • addition / subtraction

Gathering Information

• uncertainty in measurements (p565 in text)
  • precision / accuracy
    • rule of thumb - in absence of any other data estimate the precision of an analogue measuring instrument to the nearest 1/2 of the smallest graduation. This is reflected in the number of significant digits. The number of significant digits recorded is the number of significant digits which are certain plus one significant digit which is uncertain. For example if you were measuring a distance using a device with the smallest graduation in mm, then you may record a distance of 19.3 mm or 1.93 *10**1 mm. You would be certain about the 1 and 9 digits and not certain but making your best estimate at the 3 digit.
  • percentage error / percentage difference (see bottom of p565 text)
    • compares your final result to a known or predicted quantity.
• dependent and independent and control variables (see p548-549 in text)
  • CN tower example

Presenting Information

• graphing
  • Usually independent variable is presented on the x-axis (abscissa) of the graph and the dependent variable is plotted on the y-axis (ordinate) of the graph.
  • Dertermine the range of the data and select a suitable scale.
    • divisions should be convienient
    • data should be spread out as much as possible
  • Label both axes. [Variable Name, Symbol, Units]
  • Plot the data points
  • Draw a best fit straight line or smooth curve that passes through as many data points as possible.
    • Do not draw line segments to connect the dots.
  • Give the graph a title. [Fig 1, Graph of the Average Distance vs the Time of the Cart for Test 1, 354g Load]