PASCO Xplorer-GLX Users’ Guide - Manual (Page 53)

X p l o r e r G L X U s e r s ’ G u i d e 47
Plot the calculation on the horizontal axis in place of Time to create the graph
shown below. (See page 28 for instructions on selecting data for the horizontal
axis.)
Convert Units of Measure Most of the sensors used with the GLX are pro-
grammed with SI units (or the International System of Units) and, in some cases,
other common units. If you wish to make a measurement using units that are not
programmed into the sensor, create a calculation to convert the measured data.
11
For example, if you are using a Motion Sensor, which measures position in
meters, and you want to convert the measurement to centimeters, create the cal-
culation below. (To enter text, see “Num Lock” on page 50.)
position in cm = [Position(m)]*100
Calculate an Experimental Value In some experiments, it is possible to cal-
culate an experimental value based on a sensor measurement. For example, in an
experiment where a Motion Sensor measures the acceleration of an object, you
can use the Calculator to calculate the net force:
force = mass * [Acceleration (m/s/s)]
The Calculator will prompt you for the value of mass.
Compare Measurements from Two Sensors When collecting data with
two sensors, a calculation can be used to compare the separate measurements.
For example, if you are using two temperature probes, named “Temperature” and
“Temperature2,” and you want to know the temperature difference between
them, create the calculation:
[Temperature (
°
C)] - [Temperature2 (
°
C)]
Graph Linearization In some cases, such as the examples below, you may
want to linearize data so that you can use the Linear Fit tool in the Graph display
(see “Linear Fit” on page 19). To do so, use the Calculator to calculate the square,
square root, natural log, etc., of the measured data. (See “F1 Functions” on
page 48 for more information on these and other functions.)
• The graph to the right shows period (T) versus length (L) data from a simple
pendulum. The graph can be linearized by plotting T
2
versus L. The slope of
the graph (shown below on the left) is 4
π 2
/g, where g is the free-fall acceler-
ation. Alternatively, the graph can be linearized by plotting T versus . On
the graph (shown below right), the slope is .
This data plot has been time-shifted
by -14 s
11 For certain measurements (tempera-
ture, for instance), it is not necessary to
calculate a units conversion because the
sensor is programmed with other com-
mon units of measure (°C, °F, and K),
which can be selected from the units
field of any display. See pages 15
and 29.
Period vs. Length for a
simple pendulum
L
2
π
g
⁄
T vs. √⎯ L for a simple pendulum T 2 vs. L for a simple pendulum