Date: Thu, 13 Oct 2011 08:59:09

Author: Steve Wonnell

Subject: Re: another Vernier question

Post:


Hi Sam,

On Wed, 12 Oct 2011, Sam Sampere wrote:

> Ok, I've noticed this in the past, but now it's really bugging me because I'm teaching the class.
>
> If you've ever done N3 using 2 force probes, you'll notice that the
> curves are a tiny bit displaced from one another. I've attributed this
> to the timing differences, collect FP1, then FP2, then FP1, etc.

It must be something like that. It is annoying.

> Now I'm doing an impulse-momentum demo - crash a car into a piece of rubber. Plot the F-t curve and the v-t curve.
>
> I've set LP to collect 1000 pts/s. I know, the MD cannot do that, so LP sets that to 20 pts/s.
>
> I start to see the change in v maybe 10 or 15 points BEFORE there is anything on the FP. Why???
>
> Barring that, it's a beautiful experiment. Integrate F-t, measure delta v, and you get quite good agreement. I'm using LP3.8.4 if that's of any issue with a Vernier MD and a wireless FP.

Interesting. I have the MDs that plug into the LabPro, so for our
apparatus I don't recommend using them because it slows down the Force
probe data collection. But F versus t does give a nice result:

http://www.pha.jhu.edu/dept/lecdemo/img/M-n1c_1600x1200.jpg



>
> Thanks!
>
> Sam
>
>
> --------------------------
> Sam Sampere
> Syracuse University
> Department of Physics
> 201 Physics Building
> Syracuse, NY 13244
> 315-443-5999
> 315-443-9103 (fax)
>


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