Match Made in Heaven

by Professor Rich Born


Are you looking for some great physical science activities for 4th grade through junior high school students? If so, it would be well worth considering interfacing PocketLab Voyager with the "intelino smart train". Designed for all ages, intelino is intuitive with its app, has built-in sensors to provide an interactive experience for the user, and is easily programmed with color snaps that allow the user to control intelino's actions. In this lesson, your students are challenged to design an experiment to measure intelino's speed with the help of PocketLab Voyager's magnetometer. As shown in Figure 1, Voyager is mounted to the top of the intelino smart engine. Custom color snap commands set intelino's speed, and magnets are used to denote track locations where the speed changes. One device runs the PocketLab app, while another runs the intelino app. This is STEM at its best!

Figure 1 - PocketLab/intelino smart train setup

The PocketLab Voyager/intelino STEM Challenge

Here is the challenge for your students:

"Design an intelino track layout and accompanying Voyager experiment that will allow you to compare nominal intelino train speeds of 30, 40, 50, 60, and 70 cm/s to the speeds as determined by data collected from the PocketLab app. All five speeds should be obtainable from a single run of Voyager/intelino on the track layout. Once the train has been started, no more interaction with the intelino app is allowed. The intelino app can run on one device, while the PocketLab app runs on a second device. You can make use of the six provided magnets and a meter stick, as well as built-in color snap commands and custom speed snaps in the intelino 'Snap Editor'."

A Typical Solution to the PocketLab Voyager/intelino STEM Challenge

Figure 2 shows the setup used by the author of this lesson. Voyager is mounted to the top of the engine using a 3M damage-free strip. Several notations have been included as an aid to understanding the setup. Adjustments may be necessary if the number of track pieces available is more limited. The intelino train is started on the curve at the far right of this figure between the blue-white reverse command and the yellow magnet. The initial speed of "slow" (30 cm/s) is selected while the intelino app is in autopilot mode. The engine's front is facing toward the left. Between the yellow and blue magnets, the train speed is set to a nominal 30 cm/s. When the train reaches the blue magnet, it encounters a custom color snap command (white-magenta-red) that changes its speed to 40 cm/s. Therefore, it travels at a nominal speed of 40 cm/s until it reaches the next magnet and color snap command. The train continues in this fashion until it reaches the far left end of the track where it encounters a built-in slow speed command (white-green-white). It then reaches the reverse command near the end of the curve and changes direction. On the way back to the far right, the custom commands are ignored because the order of the colors in each command is the opposite of what is required by the custom commands. Upon reaching the far right, the train reverses itself and repeats the entire process over again.

During the entire process, PocketLab Voyager's magnetometer records spikes in the magnetic field magnitude each time that it passes a magnet. The time between spikes is recorded using the PocketLab app. A meter stick was used to determine the length of a piece of straight track -- 24 cm. With magnets set two straight tracks apart, the distance between magnets is therefore 48 cm. The speed is easily calculated by dividing the distance by the time. Students can then compare the nominal speeds to those determined from the PocketLab app data.

Figure 2 - Typical solution to the STEM challenge


The following 20-second video shows a run of the experiment on the author's setup. You should notice the spikes in the magnetic field strength when the intelino train and PocketLab pass by each of the magnets. The speed is easily determined by dividing the distance between magnet pairs by the time between the corresponding peak pairs. You will also notice that the time between peaks decreases as the train travels from right-to-left. However, on the return trip from left-to-right, the speed stays constant at a slow speed. Figure 3 shows this in a single snapshot.

Figure 3 - Magnetic field magnitude peaks

Data Analysis

Figure 4 shows an Excel graph created from PocketLab data collected during a typical run of the experiment. The six magnetic field peaks are shown with the time for each peak. The time for Voyager/intelino to traverse the path between the the first two magnets on the far right was 4.10 s - 2.50 s = 1.60 s. The speed is then computed by dividing the distance traveled (48 cm) by 1.60 s, with a resultant speed of 30 cm/s. In a similar manner, the remaining speeds are computed. These PocketLab speeds compare well to the speeds that were specified for the intelino custom color snap speed commands. Students could be asked to explain why the custom speeds, as determined by the PocketLab app are all consistently somewhat below the nominal color snap speeds.

Figure 4 - STEM challenge experiment results