One of our users, Christian, wondered about the centripetal (or centrifugal, depending on your reference system) force in his honey separator. He basically has got a centrifuge for his honeycombs which extracts the honey using this force, but unlike our experiment using a salad spinner, he was unable to measure the acceleration directly because it exceeds the range of the sensors in his smartphone. So, instead he attached his phone to the crank of the centrifuge and created his own phyphox experiment, which uses the gyroscope to determine the rotation speed of the crank. From this, his experiment then derives the speed of the centrifuge itself and all the forces involved, taking into account the transmission of the crank as well as the radius at which the honeycombs are placed within the centrifuge. If you are interested in this, here is a link to directly open his exeriment in phyphox and a link to download his phyphox file defining the experiment.
Thanks to Christian for sharing this unusual application with us.
Besides releasing a minor update with a bunch of fixes, there has been a lot of great coverage of phyphox over the last week. So, here they are in no particular order (well, I put the English ones at the top).
AAPT webinar: Using smartphones to teach physics
Well, this is not exactly press coverage and technically it’s not in the past seven days, but I still want to mention this at the top, because it was a great web-event by the American Association of Physics Teachers (AAPT) on December the 10th, which brought together many people from around the globe pioneering smartphone physics. Thanks a lot to AAPT’s Rebecca Vieyra for hosting the session. Hopefully, a recording will be available online soon…
Kit Betts-Masters, a physics teacher from the UK, has covered phyphox on his Youtube channel “Gorilla Physics”, which you can check out here.
The experiment, which explores centrifugal acceleration in a salad spinner, has only been added in the update before the last one. But it has become one of our favorites as few others are that simple and yet give such beautiful results.
So, here is the new update 1.0.4 with our new experiment: The acoustic stopwatch. Again, this is more a tool than a full experiment, but a very useful one. The watch starts counting when there is a noise above a (selectable) threshold and it will stop again on a second noise.
A simple usage case is a free fall experiment, in which you create the first noise when releasing a weight (for example by popping a balloon or hitting a mount) and the second sound is generated by the impact of the weight. Of course, there are some other improvements and bugfixes as well as an update to the file format (to make the acoustic stopwatch possible). You will find the full list at the end of this post.
For now, it looks like this will be the last minor 1.0.x update and I will now start working on the next major step, which will be 1.1.0. Of course, if there are some major bugs or a nice new experiment, which can easily be added, there will be a 1.0.5 inbetween, but for now I will look at the two major changes: Better graphs (zooming, multi-data etc.) and a better workflow for custom experiments without transferring the files manually.
Unfortunately, I cannot tell when this will be ready. This depends on how much time I am able to invest and on how complex the new features are. Also, the graphs will require some testing before an official release – but I will share info on the progress.
Now for the changelog:
New experiment: Acoustic stopwatch
More options when exporting in CSV format: There now are variants with a comma as decimal point and the number format is now consistent across both platforms.
Grey out experiments that are unavailable
Add video links to the experiment menu as well (or any link marked as highlight)
Changes to the phyphox file format
New analysis module: if
New view element: button
New initializing attribute for buffers
Fixes for Android
Improved behavior when hiding keyboard
Fix possible crash when switching to different app
Update views in stopped state
Fix auto-orientation not respecting system setting
Fix opening phyphox:// URLs with parameters
Fix for the (half-official) Bluetooth support. Note, that this will changed and replaced by Bluetooth 4.0 / BLE in the future.
Apply size setting of value view element to the remote interface.
Fixes for iOS
Fix magnetometer calibration factor. (Note: We are using the uncalibrated magnetometer values, which may be way off from what you expect for small fields like the earth’s magnetic field, but which should be good for stronger field. However, we might switch to the calibrated one in the future to avoid confusion, but which might introduce other problems.)
Fix for not stripping trailing zeros if a fixed number of digits is defined for a value view element
In this new update two new experiments have been added: Centrifugal acceleration and inclination. While the latter is just a tool to measure the inclination of a plane, centrifugal acceleration is a lot of fun while being amazingly simple. Just rotate your phone at a fixed radius r at different angular velocities ω to visualize the relation of the centrifugal acceleration a.
In other words: Just put your phone into a salad spinner or on a carrousel to show a = r·ω². (The picture shows an earlier version of the experiment using a salad spinner)
Besides that, 1.0.3 introduces some new analysis modules (the wiki will be updated in the next few hours) and addresses many bugs, especially two common crashes on iOS. Here is the full changelog:
New experiments: Centrifugal force and inclination
Simple view for raw sensors, just giving numbers
Improved descriptions and labels for several experiments
Better time axis calculation in elevator experiment
Updated experiment file format to 1.2: New modules for statistics and trigonometry. Also more control over value and graph view elements.
Fixes on iOS
Disappearing view elements after rotation or scrolling
Crash when starting web interface on iOS8
Crash when entering zeros in Doppler effect
Crash in autocorrelation module (experiments “Spring”, “Pendulum” and “Autocorrelation”)
Missing data points in remote interface (mostly elevator and roll)
Could not open external experiments on iOS8
Strip white-spaces from description
Fixes on Android
Fix wrong play-button animation after screen being turned off
Do not show the save-locally-dialog again after rotation
Show “-” instead of “NaN” when no data is available
Improved reliability of remote interface when doing partial data updates
Fix possible crash when switching apps while graph is visible
Fix crash when closing experiment without dismissing the info-tooltip
We have just released version 1.0.2 which mostly adds some guides to alleviate some typical confusion for new users:
Hint to guide inexperienced users to the experiment info.
Ask if externally loaded experiment should be added to collection. (You can still do so later via the menu as before.)
Disable back swipe gesture to avoid involuntarily closing an experiment when swiping between tabs. (iOS only)
Limit min/max of allowed values in some experiments (phyphox file format has been updated for this)
Values entered in experiments are now only used for calculations after the user confirms the input (hitting the confirmation button on the virtual keyboard) or changes the focus away from the edit box. This behaviour now matches the one from the iOS version and prevents unnecessary recalculations while entering numbers. (Android only)
Fix decimal values not being allowed. (iOS only)
Fix problematic recalculation when clearing buffer. (iOS only)
Handle flawed phyphox files more gracefully and report errors. This will be improved further in future updates. (iOS only)