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Static Friction Coefficient
(09-04-2020, 06:07 PM)SJS Wrote: Dear CheYin,

in a workshop we have created a very quick-and-dirty version of this experiment. Therefore I cannot recommend this experiment without reservation, because it is not proper for the following reasons:

It is limited to the maximum angle from the moment the motion stopwatch is triggered (lines 164-167). Assuming that the angle is increased during the slide, the increased angle is used in the further calculation and not the angle from the moment of triggering. Therefore the angle must not be increased from the moment of slipping.
Regarding the triggering: the if-query (lines 157-162) only asks if the timer of the motion stopwatch is running; this means that as soon as the motion stopwatch takes a time measurement (even a later one!), the corresponding angle is always measured as well, although it seems as if the measurement has already been finished.
Therefore it is possible to start another measurement unintentionally; for example, if the smarpthone already slipped from the inclined plane, a new measurement can be started unintentionally when lifting (= new acceleration) and a different angle could be processed (cp. if-query). This means that the measurement must be stopped via the ||-button before the smartphone is lifted.

So please use the attached file with some caution. It would be much more elegant to store and process an angle for each activation of the trigger.

Best wishes, Sebastian.

PS: i assumed the same as Jens, that the motion stopwatch should show the angle instead of the time.

Thank you! Sebastian and SJS!
I have tried the file. It was awesome! Thank you for responding my demand.

Although my wish was that motion stopwatch could stop taking time measurement after being triggered (when the phone start to slide)
,the file you made for me is sufficient to accomplish my desire!

I will try to adjust the motion stop watch to show the angle instead of the time in future!
Thank you so much!

Messages In This Thread
Static Friction Coefficient - by chcheyin - 08-30-2020, 05:13 AM
RE: Static Friction Coefficient - by chcheyin - 09-03-2020, 04:13 PM
RE: Static Friction Coefficient - by SJS - 09-04-2020, 06:07 PM
RE: Static Friction Coefficient - by chcheyin - 09-12-2020, 06:26 PM

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