11-01-2021, 12:35 AM
Hi. I am a volunteer for a program that has scientists/engineers visit schools to inspire them into STEM, largely by doing experiments in the classroom with the students. My post here is a contribution to an experiment idea in this context, but I also have some questions.
The experiment, or design challenge, targeted to 10-12 year old students, is to have the students design effective crash barrier structures out of newsprint, which will assessed by running a (weighted) toy truck down a ramp that crashes into the barrier that they made which is placed it in front of a hard stop. A smartphone fixed to the toy and running the Phyphox acceleration experiment will be used to record the maximum acceleration of the impact, and thus rate the performance of the barrier. I think the timed run with the beeping countdown will add a nice touch to the experiment. This would be a fancy version of the classic egg drop experiment, but rather than a potentially messy pass/fail measurement, would actually provide a numeric ranking suitable for this purpose.
I am still in the process of getting familiar with how the phone (a Samsung Galaxy A5) reacts under different impact events. So far I notice that the maximum recordable acceleration seems to be about 90 m/s2, and it doesn't take much of an "impact" of the toy on the hard stop to reach that. Is this range a physical limitation of the sensor? Also, there seems some non-repeatability in the measurements at the higher acceleration values (for two similar hard impacts, one may record 90 and one 40 m/s2). Perhaps an effect of the sampling rate or missed sampling points? For more moderate impacts, the measurements seem repeatable, but would this type of experiment benefit from more, or perhaps less, data smoothing? Hopefully most students will make barriers soft enough to be in the working range of the phone. In any case, I think it will be fun for the students.
The experiment, or design challenge, targeted to 10-12 year old students, is to have the students design effective crash barrier structures out of newsprint, which will assessed by running a (weighted) toy truck down a ramp that crashes into the barrier that they made which is placed it in front of a hard stop. A smartphone fixed to the toy and running the Phyphox acceleration experiment will be used to record the maximum acceleration of the impact, and thus rate the performance of the barrier. I think the timed run with the beeping countdown will add a nice touch to the experiment. This would be a fancy version of the classic egg drop experiment, but rather than a potentially messy pass/fail measurement, would actually provide a numeric ranking suitable for this purpose.
I am still in the process of getting familiar with how the phone (a Samsung Galaxy A5) reacts under different impact events. So far I notice that the maximum recordable acceleration seems to be about 90 m/s2, and it doesn't take much of an "impact" of the toy on the hard stop to reach that. Is this range a physical limitation of the sensor? Also, there seems some non-repeatability in the measurements at the higher acceleration values (for two similar hard impacts, one may record 90 and one 40 m/s2). Perhaps an effect of the sampling rate or missed sampling points? For more moderate impacts, the measurements seem repeatable, but would this type of experiment benefit from more, or perhaps less, data smoothing? Hopefully most students will make barriers soft enough to be in the working range of the phone. In any case, I think it will be fun for the students.