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Re: [Phys-L] impacts


On 2016/Nov/28, at 15:42, John Gastineau <jgastineau@vernier.com> wrote:


A force sensor can be modeled by a mass on a spring. From the compression you know the force. But, that also means that the darn thing has a resonant frequency. That limits the response time.


From my experience w/ ballistic galvos [1] adding an elastomer wouldn’t help by critically damping. I suppose.


bc, remembers the term CDRX.


p.s. probably already reported: I demo’d [2] a dropping magnet ina Cu tube hanging from the Vernier force sensor. Then I extended the PVC tube inside the Cu pipe. When the magnet “hit” the Cu part the system oscillated. I mistakenly thought it was the magnet bouncing. No no. John Mallinckrodt explained. I contacted Vernier; either David or John gave me the force constant.

[1] Got a couple w/ telescope, etc. surplussed from UCSC, originally from (probably) Berkeley. (I used one to measure capacitance in my Sophomore or Jr. lab. (UCSB, ca. 1957) Calibrated w/ std. cell the L&N potentiometer.)
[2] A few years ago at a SoCal-AAPT mtng. This was well before similar reported in the “The Physics Teacher”.