danaleeling

Demos graphing calculator on the web (desktop, laptop) includes a regression tool. The tool is not yet in the mobile app. To use the tool on a mobile device use the mobile browser to open: https://www.desmos.com/calculator The regression tool works with tables. The tool is an icon at the upper left side of the table. The tool opens as a linear regression. Other regression options are available. To the right of the equation is an icon that copies the equation out to a new line. Editing that to f(x) notation results in a function that accepts inputs. Note that the above was done on mobile device using the mobile browser, not the Desmos app.  The graph above was autoscaled using the autoscale on the table.

In physical science each laboratory group is producing their own measurements of a phenomenon and using Desmos to graph their data and obtain a best fit mathematical model.  Data The above data are the times for a ball to fall from the heights in the right hand column. Five groups performed the experiment generating five data tables. I wanted to make a single table that used the mean or median values for each time at each height and I did not want to manually calculate those means or medians.  The basic structure can be seen above. t₁[1] retrieves the value of t₁ in row one of the table. t₁[2] retrieves the value in the second row of the table. Note that the missing three meter drop height is intentional, that drop height is difficult to obtain due to the geometry of the classroom building.  Cells in a table can handle mathematical operations and functions. Above two of the rows are calculating the mean time from all five tables using an arithmetic function, two of the r...

Summer term with online lectures and residential labs meant that the introduction to waves using a RipStik could only be presented via a video.  The evening prior to laboratory nine I found that Desmos  could regress to a sine function if given the five points seen in the image above: three centerline points and the peak of a crest and the bottom of a trough. The regression remains fairly stable for small perturbations of the data points. Prior experiments had yielded unstable results often with extremely high frequencies. This would form the gist of laboratory nine. I started the build of the poster paper inside and then moved outside. Wind, even the slightest of breezes, is problematic.  Scotch tape was used to assemble an eight sheet run. Each sheet is 83 cm long, thus the whole run was 664 cm. The wind held off long enough to make the run. The run was made barefoot as notes from prior terms on runs made during a Monday lecture-demonstration suggested a larger amplitud...

Waves opened with a four sheet RipStik wave on the sidewalk. The speed was reduced to push the amplitude. The run requires a stopwatch and a tape measure for use post-run. Reducing the forward speed and focusing on deep cycling of the RipStik enhanced the wave form. Wavelength was covered first and then the amplitude. The average wavelength was computed from 3.35 meters divided by 2.5 waves. The students decided that 2.5 waves were present. Then the period and frequency. Wrap included the sine function and the wave speed (seen on the leftmost sheet above). Equipment for Wednesday. Wednesday wrapped up with an oscilloscope app to show that sound waves are sine waves two. A function generator app was also used. Thursday's measurement of the speed of sound requires a fair amount of equipment and I still forgot to bring a pen. Not shown: a pocket knife to cut the tape in the event field repairs to the clappers might have been needed. Zero ...