# Day 144: Electric Force (Paradigm) Lab and “Ba Bam!!!”

Today we whiteboarded the last question on the charge practice sheet.  Here is it:

It is chance to have the students confronted with another N3L question.  Most of the students saw that is the electric force exerted on A, by B was the same size as the electric force exerted on B, by A.

It also provides the perfect introduction to an electric force experiment.  I simply ask what the students think the magnitude of the electric force depends on.  They quickly suggest the amount of charge on each balloon, and the distance separating the two objects.  And… right there is the purpose of the experiment… determine the relationship between the electrostatic force and the charge on each object and the relationship between the electrostatic force and the distance separating the two objects.

We use a simulation to gather the data because, well, because it is MUCH easier than trying to really get accurate and quantifiable data. Here is the handout Electrical Force Simulation(13-14)I give the students, it includes a screen shot the simulation screen.  Here is a link to where I found the simulation last year.  I like this one because it does not give too much away and allows a variety of charges and distances.  Tomorrow we WB the results. and develop Coulomb’s Law.

General Physics:

Today we finished the How Hot Are Your Hot Wheels activity; I told the students at what point I wanted them to predict the velocity of the car, so where I would place the photogate.  If you read yesterday’s post, I was concerned about getting accurate velocity data needed in order to determine the dissipated energy and the frictional force.  Well here is screenshot of a group that used a Vernier Photogate to gather the data and to predict and check the velocity.

That’s what we call a “Ba Bam”… nailed it.  Here is a screen shot of a group that used the BeeSpy photogate for the entire experiment:

And again, another Ba BAM!

Moral of the story, if the students are careful when gathering the data, the results are awesome.  Seriously, how awesome are those results??  Pretty ‘darn’ awesome.  PHYSICS ROCKS!

SIDEBAR —> I still have to collect some from each class, and I’m pretty sure there will be a few that are not that close.