Day 137: WTH, this impulse data is UGLY.

Advanced Physics:

The plan for this class period was to WB the results from the impulse vs. change in momentum experiment we conducted on Friday.  The results were overwhelmingly UGLY.  I had one or two groups (of 7) in each group that ended up with a slope of approximately 1.0 as was expected.  I re-ran the experiment during my prep hour. Here is a screen shot of that the data gathering looks like:

Screen Shot 2015-04-14 at 12.15.56 PM

and now a shot of my impulse vs. change in momentum graph:

Screen Shot 2015-04-14 at 12.18.50 PM

My slope is 0.984…. so close enough to one for me.  So why did most of my kids get ugly data?  I think I know what happened.  First of all, they did not did not use an instantaneous velocity at the time the collision started, that’s what I did.  But a bigger issue was how we measured force.  I screwed up and let them put the hook or bumper in to the WDSS.  The issue was some of them screwed the extender or the hook/bumper in way too tightly.  Some of the force sensors were reading 15-20 N before they even zeroed it. Now my concern is that they might have damaged the internal sensor 😦


General Physics:

Today was practice with the kinetic energy model.  We WB’ed a practice sheet, worked in small groups on the first energy conservation problem, and did a pre-lab discussion for the gravitational energy experiment we will do the next class meeting. Here is a screen shot of the COE problem:

Screen Shot 2015-04-14 at 12.34.57 PM


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