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Did the bookstore run out of Lab Manuals? In case it has not yet gotten more ...

<= you may print your own copy of Lab 1 and/or Lab 2 from these pdf files

  <= . . . (right-click, "open", then print)

  General Physics I Lab . . . Foltz section 6
    Phy.202 . . . W 3pm - 4:50pm
Class Meets in :    Science 100 for 1 hour + 50 minutes
My office:   Science 159 (below ramp to 3rd Ave)     my e-mail :   foltzc@marshall.edu

Why do we have Physics Lab? To confront Nature as she really is, rather than just as our idealizations.
Our eventual goal is for us all to be able to observe and measure real phenomena;
. . . to be able to design experiments that can be successfully implemented;
. . . to organize and display data to make relations obviously apparent;
. . . to critically analyze results, and infer sources of error and uncertainty;
. . . to extract conclusions from results, and communicate them to others.

We are trying to gain expertise (practice) with 4 tools:

• words (some common American phrases are misleading/ambiguous)
• diagrams (vectors & labels)
• graphs (abbreviation symbols & Units)
• equations (definitions today, cause-effect relations begin week 5)

• Quantity = a property that can be added and/or subtracted (numerically)
• Place = x ; also called location or position : where it is, relative to (as seen by) the observer: ± direction!
• Vector = something with a length that points in a direction; draw as an arrow
      place vector: arrow tail is at the observer, tip is at the observed (object)
• Change = Δ; making later not the same as before; (later − before)
• Variable = something that varies , or the abbreviated symbol that stands for it
      example: x_t means that place is different at different times
• Displacement = Δx; dis new place, not de old place; (x_new − x_old); time end-points!
      use adjectives to distinguish the time that a variable has some special value   (new, old)
      . . . often written as subscripts ... average; maximum, minimum; before, after ...
• Vector Diagram : for some time interval ... the before vector + the change vector = the after vector
      the change vector is added , by placing its tail at the before vector's tip ... the after vector's tail is at the before vector's tail (the diagram's origin)
      several displacements can be added in sequence, one step at a time, with its tail-at-the-previous-tip ... like a kid's connect-the-dots number drawing
• Distance = the path length that has been (or will be) traveled; always positive
• Away = away from the detector; distance from it becoming longer
• Toward = toward the detector; distance becoming shorter (closer to zero)
• Rate = any change divided by the duration (time change) in which it occurred
• Speed = v; how fast the travel rate is (≈ 1/slowness)
• Motion = what you have while your mass is moving; momentum
• Momentum = mass moving with some velocity ... p = m v   is a "conserved" "dynamic" vector.
      explanation (reasoning & understanding) is founded on momentum (mass moving)
• Velocity = v ; speed in a direction, is a vector . . . motion descriptions refer to velocity
      velocity vector tail should be at the mass center (but is usually offset for clarity)
• Uniform = the same; either each one is the same, or the same at every place
        (we actually want different motions during each run)
• Constant = always the same, through a time duration
• Steadily = continuing in the same manner through a time duration
        constant place means that the velocity is steadily zero, but
        constant velocity means that the place is steadily changing, and
        constant acceleration means the velocity is steadily changing!
• Value = the particular measurement result for a quantity, at some time(s)
• Slope = rise/run; slope on any graph vs. time is the change rate ... slope on any graph vs. location is the gradient
        the slope on an x_t graph, is the value (at that time) on its v_t graph.
• Curvature = "slope of the slope"; curvature on its x_t graph, is the slope on its v_t graph , and is the value on its a_t graph .
• Acceleration = a ; the slope on a v_t graph is the value on the a_t graph.
• Component = the portion of a (diagonal) vector that is in some particular direction ; often parallel and perpendicular to a surface or acceleration
      use a trig triangle to split a diagonal vector into its components ... " s o/h c a/h t o/a "

• Force = a push or pull vector caused by a subject , applied to the object ; has strength (magnitude) in a direction
      Forces are Summed   ΣF   to include all that are applied to the object ... (which is what makes its momentum change over time)
      Draw pulling Forces with their arrow tail at the contact place ; draw pushing Forces with their arrow tip at the contact place
      each Force should be labeled (named) for the subject item that produces it ... not the item it is being applied to
  • gravity is a field Force; no contact required ... F_grav = m g . . . gravity field g = g (down) . . . has intensity g = 9.8 ^N/_kg , around here .
        all other Forces this semester require contact ... touching ... Pressure Forces press (perpendicularly) thru the contact surface Area
  • except for friction, which is (or rather, macroscopically appears to be) along (parallel) the contact surface , opposite the slide (or slide tendancy)
  • Tension Forces from Thread or strings or ropes or cords or cables ; at each end, the Force is inward toward the rope center
        . . . F_rope = P·A (inward)   ... until a maximum P, which breaks the rope ... rope having larger cross-section Area allows more Tension
  • support Forces from table-top or floor or track or ramp, are F_table = P·A (outward from the track into the cart)   ... until a maximum P, which ruins the wheels
  • springs apply Forces opposite to their stretch , F_elastic = −k·s   ; k is the spring's "stiffness" , s is the stretch for that spring end.
    . . . "Normal" is a direction (perpendicular to the surface) , not a subject that can cause a Force
    . . . "centripetal" is a direction (inward toward the center = opposite the outward radial direction) , not a subject
• Impulse = J ; Force accumulated for a while ... F_average·Δt . . . is the Area on its F_t graph .
      the vector sum   ΣJ causes   Δp   = Δ(mv) .
• Work = W ; Force collected for a ways ... F_average·Δx . . . its scalar total ΣW causes   ΔKE
      a conservative Force has an associated Potential Energy ... the Work that it could potentially do , if the object moved along the Force direction
      . . . PE_gravity = mg h . . . if the object might fall from height h to height 0 ;
      . . . PE_elastic = ½ k s² . . . if the object might move so the spring's stretch s becomes 0;
      . . . Friction has no PE function, because its Force direction depends on velocity's direction ... so its Work is not a function of only Δx .

Comments applicable to all Phy.202 Labs:

A. Workbook predictions & explanations are intended to be made by each student individually, not consulting with others
. . . only after all team members have written their predictions, then compare your answers
. . . then discuss (argue) until the team reaches consensus of correctness − you do not need to agree on "best wording"!

B. The 2 pages of Homework Questions (textbook-like) must be answered by yourself , in your own words.
  by yourself means :
  *   while NOT looking at anything that anybody else wrote down about it
  *   while NOT listening to anybody else talk about it
  *   while NOT looking at notes that you wrote , while someone else was talking about it.

. . . if you don't know how to answer a Lab Homework question :
    1.(first) a. look in the workbook to see where you did something similar
    1.(first) b. study your notes from 201 and/or your textbook for 201 (lecture portion)
    2.(second) see your lab instructor for hints and suggestions
    . . . . (do not expect to be told outright what the answer is, nor what equation to use ! )
    2.(second) discuss the concepts with your study partner
    . . . . (in words only ; no "formulas" , no "symbols" or "letters" , no taking notes meanwhile )
    4.(fourth) see your lecture instructor for hints and suggestions
    . . . . (do not expect to be told what the answer is, nor what equation to use ! )

C. The "1 page" of Conclusion on a separate sheet is to be written by yourself (as defined above) . . . include :
  a   how the key quantities (that the lab investigated) are supposed to be related to one another (e.g, the "Law")
  b   whether those relationships were , or were not , shown by your measurements and analysis (i.e, was it true?)
  c   how close the theory prediction came to the experimental measurement ... that is, how does theory compare to experiment (divide to compare; how close to "1"?)
  d   were there "special circumstances" that might modify the expected relationship (i.e, why wasn't it exactly right?)
  +   what measurements were probably low precision, low accuracy, low repeatability? How uncertain (%) were the worst ones? ... does this explain "c" (↑) ?
  −   (always optional) specific constructive comments about the lab ... re: clarity, difficulty, duration, fun-ness, rewarding, ...
      . . . then STOP . . . don't B__S__ just to fill the page !

      You should treat this Conclusion as an opportunity to practice using Physics vocabulary correctly !