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Physics Graphing Using Excel
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.450.00
0.20
0.40
0.60
0.80
1.00
1.20
f(x) = 2.55x - 0.03
Ball Rolling off Table
time (s)
Ho
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of
Dis
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t (m
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Advantages of Graphing with Spreadsheet Programs
• Can be fast. Handles lots of data and multiple calculations.
• Precise calculation of equations.
Disadvantages of Graphing with Spreadsheet Programs
• Students still need to be able to graph by hand.
• Students often do not use the correct type of graph or leave the equation in the proper format.
• Computers can not assess the importance of irregular data points.
To graph data, it must be inputted into a spreadsheet program.Here is an example of data
collected by a student.
To select the data to be graphed, left click on the first cell with the data you want on the x-axis and hold down the button while you move down over the data. To
select the y-data, hold down the ctrl button then left click and
drag down.
Include a descriptive title, and label each axis. For example, the title Dy vs t is
not descriptive. Be sure to include units.
Once you have a graph, double click on a data point.
• Give a value for the x and y error bars(the uncertainty). Generally the uncertainty should be half the smallest unit measurable by your measuring device. You may have to calculate the value on the spreadsheet and input using the “custom” selection.
Choose the correct type of treadline. For linear relationships like F=ma, choose “linear”. For
exponential relationships like d = ½ at2 + Vit choose “exponential”
(Vi = 0) or “polynomial” (Vi non
zero).
Under options select that the equation be shown on the graph.
Adjust the treadline as is appropriate for the data.
Once you have an equation, click on it. Change the variables from x and y to the quantities you are graphing, like force or position.
For polynomial equations, change the significant figures to a
reasonable number now. If the curve is very close to all the data
points you would use more significant figures than if it is far.
For linear functions, use the uncertainty of the slope to
determine precision.
Include units in your equation. Think “what are the units of the rise and run? What are the units of the slope and intercept?” If
the y variable has units of m and the x variable has units of s then the slope will have units of m/s
or ms-1 and the intercept will have units of m.
Uncertainty
Two ways to determine uncertainty of a graph:
1. LINEST function (Bonus)
2. Max-Min lines (IB required)
1. To determine the uncertainty in the slope and y-intercept.- Go back to the spreadsheet.
- Select 4 cells in a square- type =LINEST(y values, x
values,TRUE,TRUE)- press Ctrl/Shift/Enter at the
same time for PC or the command key for Macs
For the example the slope is 2.55 and the uncertainty is 0.07. The
y-intercept is –0.03 with an uncertainty of 0.02. Note: the
uncertainty dictates the Sig figs. Go to your graph and include the
uncertainty on your equation.
IBers
2. Draw Max/Min lines on your graph using the drawing tools or a pen.
Calculate the slope of the two lines by hand and half the difference is your uncertainty.
Remember, uncertainty is to one digit only and the value is rounded to the precision of the
uncertainty.
11.1 +/- 2.1 BAD 11 +/- 2 GOOD
Vertical Velocity of Basketball
Vy Vy = (-11+/- 2) m/s2 t + (5+/-1) m/s
(m/s)
Time (s)
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
-6.00
-4.00
-2.00
0.00
2.00
4.00
6.00
Check that the graph is clear with the equation easily read. If necessary, resize portions of the graph by moving a corner or side.
Copy the data and calculations into a table in your report.
Display the equations you used (copy and paste them from
Excel)
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.450.00
0.20
0.40
0.60
0.80
1.00
1.20
f(x) = 2.55x - 0.03
Ball Rolling off Table
time (s)
Ho
rizo
nta
l C
om
po
ne
nt
of
Dis
pla
cem
en
t (m
)