Date: Thu, 13 Oct 2011 07:27:16

Author: Sam Sampere

Subject: Re: another Vernier question

Post:

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Did that - same thing. I typically use x-t to extract velocities and accele=
rations. For this, it's much quicker and easier to grab the velocities jus=
t before and just after collision off the v-t graph. There is a real time d=
ifference between the data from the two probes, and I have a sneaky suspici=
on it's the bluetooth radio.

Sam

________________________________
From: tap-l-owner@lists.ncsu.edu [tap-l-owner@lists.ncsu.edu] On Behalf Of =
Tom Kramer [tmkramer@alum.mit.edu]
Sent: Thursday, October 13, 2011 3:35 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] another Vernier question

I like to use the actual data and not "massaged" data. Try plotting x vs t =
and the F vs t curve and see if the discrepency is still apparent.
-Tom


On 12 Oct 2011, at 6:36 PM, Sam Sampere wrote:

Ok, I=92ve noticed this in the past, but now it=92s really bugging me becau=
se I=92m teaching the class.

If you=92ve ever done N3 using 2 force probes, you=92ll notice that the cur=
ves are a tiny bit displaced from one another. I=92ve attributed this to th=
e timing differences, collect FP1, then FP2, then FP1, etc.

Now I=92m doing an impulse-momentum demo =96 crash a car into a piece of ru=
bber. Plot the F-t curve and the v-t curve.

I=92ve set LP to collect 1000 pts/s. I know, the MD cannot do that, so LP s=
ets that to 20 pts/s.

I start to see the change in v maybe 10 or 15 points BEFORE there is anythi=
ng on the FP. Why???

Barring that, it=92s a beautiful experiment. Integrate F-t, measure delta v=
, and you get quite good agreement. I=92m using LP3.8.4 if that=92s of any =
issue with a Vernier MD and a wireless FP.

Thanks!

Sam



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Did that - same thing. I typically use x-t to extract velocities and a=
ccelerations. For this, it's much quicker and easier to grab the =
;velocities just before and just after collision off the v-t graph. There i=
s a real time difference between the data
from the two probes, and I have a sneaky suspicion it's the bluetooth radi=
o.

Sam
=



From: tap-l-owner=
@lists.ncsu.edu [tap-l-owner@lists.ncsu.edu] On Behalf Of Tom Kramer [tmkra=
mer@alum.mit.edu]
Sent: Thursday, October 13, 2011 3:35 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] another Vernier question



I like to use the actual data and not "massaged" data. Try p=
lotting x vs t and the F vs t curve and see if the discrepency is still app=
arent.
-Tom



On 12 Oct 2011, at 6:36 PM, Sam Sampere wrote:




Ok, I=92ve noticed this in the past, but now it=92s really bugging me becau=
se I=92m teaching the class.



If you=92ve ever done N3 using 2 force probes, you=92ll notice that the cur=
ves are a tiny bit displaced from one another. I=92ve attributed this to th=
e timing differences, collect FP1, then FP2, then FP1, etc.



Now I=92m doing an impulse-momentum demo =96 crash a car into a piece of ru=
bber. Plot the F-t curve and the v-t curve.



I=92ve set LP to collect 1000 pts/s. I know, the MD cannot do that, so LP s=
ets that to 20 pts/s.



I start to see the change in v maybe 10 or 15 points BEFORE there is anythi=
ng on the FP. Why???



Barring that, it=92s a beautiful experiment. Integrate F-t, measure delta v=
, and you get quite good agreement. I=92m using LP3.8.4 if that=92s of any =
issue with a Vernier MD and a wireless FP.



Thanks!



Sam














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