Who Are YOU
Calling Passive
Regressive?
Brad Langdale
blangdale@psd70.ab.ca
@b_langdale
www.ldindustries.ca
1:00-2:00
Empire Theatres 5
Graphical Analysis
and Regressions in
Physics 30
And why do we graph,
Bruce?
Physics 30 Example 1:
Curve Straightening Coulomb’s Law
• Given: data of electric
forces and charge
separation
• Graph: Fg vs r, Fg vs. r-2
• Analyze: By finding the
slope of the line of best fit
(allows us to find either k
or q1 q2)
Data, worksheets and
explanations of curve
straightening available at
www.ldindustries.ca.
Graphing using the TI-83/4
1. From the main
screen, press
STAT, then press
ENTER on Edit…
2. This is the list
menu. Enter the
values of x in L1
and y in L2. To clear
out a large number
of old data points,
scroll up to the L1
or L2 title, press
CLEAR then
ENTER.
3. You can now view
your graph. Press
Y=, clear out any old
equations you might
have entered in, then
scroll up to Plot 1
and press ENTER
until it turns black.
4. Use the WINDOW
functions as needed to
see your graph. The
dots should form a
rough line.
Graphing using the TI-83/4
5. Press STAT, then
scroll one right to
CALC, scroll down
and press ENTER on
LinReg (ax+b). This
is the Linear
Regression feature.
6. If you have no other
data entered into your
calculator, you can just
press ENTER. If you have
other data in the Stat Plot
menu, enter in (L1, L2)
behind the LinReg(ax+b)
command, then press
ENTER.
7. This is your
regression equation.
The value of “a” is the
slope, the value of “b”
is the y-intercept.
To see how this
equation matches your
data, enter it into the
Y= menu by hand…
8. …or while in the Y=
screen by pressing
VARS, scrolling down
to Statistics…, pressing
ENTER then scrolling
right to EQ and hitting
ENTER on RegEq. If
all went well, the
plotted points should
match the line.
Physics 30 Example 2:
Finding the Index of Refraction of a
Medium
• Given: angles of incidence
and refraction of a
medium
• Graph: sin(θi) vs sin(θr)
• Analyze: find n by
calculating the slope of
the graph
Graphing Using Microsoft Excel
1. Open a new document.
2. Enter the data to be
graphed. The first column
will be the x and the second
will be the y.
*Note: students can enter in
data in degrees and have
Excel take the sine of each
angle for them.
3. Highlight the two data
columns you want to graph.
4. Under “Insert”, choose
“scatter graph”.
It doesn’t matter much
which graph you
choose now, because
you’re going to
change it in a second.
5. Choose the
graph format
that has the
little Fx on it.
This one will
display the
regression
equation.
6. Format as
needed.
Physics 30 Example 3:
Determining the Focal Length of a
Convergent Lens
• Given: distances from the lens to the object
and image
• Graph: 1/di vs 1/do
• Analyze: find y-intercept to determine focal
length.
Graphing Using Google Drive’s
Spreadsheet
1. Open a new document.
2. Enter the data to be
graphed. The first column
will be the x and the second
will be the y.
*Note: students can enter in data
as regular di and do values, then
have the spreadsheet
reciprocate for them.
3. You can get a graph by clicking “Insert” and “Chart”,
but putting on the line of best fit is an ugly
process…
4. So you can just use the =INTERCEPT( feature to find
the Y-intercept (the program can’t calculate xintercepts easily either)
Physics 20 Example:
Determine Gravitational Field Strength
from a Pendulum
• Given: varying lengths
and periods of a
pendulum
• Graph: T vs √L
• Analyze: find g by
rearranging
and finding slope.
Trial Trial Trial Trial Trial Trial Trial Trial
1
2
3
4
5
6
7
8
L (m) 0.81 0.74 0.53 0.46 0.33 0.23 0.15 0.07
L
(m1/2 0.90 0.86 0.73 0.68 0.57 0.48 0.39 0.26
)
0.80 0.59
T (s) 1.76 1.67 1.45 1.31 1.15 1.01 0
0
• These graph nicely in any program, but I like
Excel (if you have easy access to it) because you
can let the kids do a bit of experimentation.
www.ldindustries.ca
-This presentation, with a Student Guide to
Graphing and Examples
-Physics 20 Lab Manual (with sample data)
-Physics 30 Lab Manual (with sample data)
-The 14 Labs You Have to Know in Physics 30
-Student resource: diploma-style problems in
testing mandated lab skills in Physics 30
-Notes, Assignments, YouTube Videos
blangdale@psd70.ab.ca
-Lab quizzes, other secured resources
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