Day 117: Are you kidding? It’s that easy? and The Sledder Lab

Advanced Physics:

Today we summarized the four main energy models; Eelas, Ek, Eg, and Ediss. After this we finally looked at two COE sample problems.  The first one was this:

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It was the same problem I gave the students to introduce the energy unit.  At the time, they solved it (or attempted to) with kinematics and dynamics.  It is about 15 steps to get it done.  I mentioned at the time, we could probably do it in in 2 or 3 steps.  So today was the day to show them that.  They caught on right away… decide your initial and final situations, draw the energy bars so you can write the energy equation, then solve.  For this problem it is Eg (initial) = Ediss (final).  From there I STRONGLY suggested they use substitution… that COE equation boils down to h=μk*Δd.  (There is another step in this, it is to use theΔd and the 70cm rough patch length to find the final resting spot, but that was not thee important part of the lesson.)

In many of the classes I heard comments like the title of the post and that’s actually pretty cool.  One of the reasons I like substitution is that it really helps kids with conceptual questiions like… what happens to the distance is slides if I double the mass?  Well, nothing, mass cancels out.

The second problem was predicting the velocity of a pendulum at the bottom of it’s swing.  This one is equally simple and then we actually check it with a bowling ball pendulum hanging from the ceiling.  We use a Vernier ‘laser-gate’ with one gate timing to check the prediction.  It’s typically very close, but smaller, because there is a tiny bit f energy dissipated.  It provides a chance for us to do this demo:

 

 

General Physics:

We discussed the N2L assessment the students took yesterday, then did a fair amount of discussion to get ready for the ‘deployment’ activity.  The assessment was a sledder on a frictionless hill, not realistic at all, because there IS friction.  The goal of the experiment is to determine the coefficient of friction for a sled and the snow.  Yep, we’re going sledding tomorrow.

Through the course of the discussion, we see that we need the angle of the hill,  the combined mass of the sledder and sled, and the acceleration.  To determine the acceleration, we ill be using the LabQuest2 x-accelerometer.  It was absolutely incredible today using the LabQuest Viewer software and our wifi network to show hte students how to set-up and use the LabQuest2.   Way to go Vernier, as always, you guys ROCK.

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Day 38: Holy **** Vernier Data Sharing Rocks

Advanced Physics:

As I explained yesterday, we are working our way through an activity with the phan cart.  The two main objectives are to master making the (kinematic) stack-o-graphs for accelerated motion and to learn to solve constant acceleration problems graphically.   Yesterday when I asked the class to graphically determine the acceleration  from one of the phan cart trials, one (maybe two) group(s) of students realized data was needed from the velocity-time graph. They asked me to provide two points so they could calculate the slope.

The next problem I was planning to ask them to solve was to use the velocity-time graph to determine the change in position during the time interval the cart was out of my hand. (I let it go and then caught it a bit later.)

Last night, after I wrote my post,  I decided to play a bit with a LabQuest 2 and motion detector I brought home.   I knew the LQ2 could share data and set up it’s own wifi, but I had never bothered to really try it in class.  As I was reading some help files from the Vernier site, I learned that the new version of Logger Pro (I’m running 3.8.6.2) has a Data Share feature (found under the File menu).  So I decided to give it a try in my classes.

All that I needed to do was to have each group login and open a browser window. I displayed the URL established under the Data Share option on my Smart board, the students enter it and voila… my data shows up on their screen!  (It could also show up on an iPad, or iPhone…)

At first I was a bit bummed that the graphs were not displayed in Logger Pro, even though that was what I was running, the Data Share analysis tools are not as good as the Logger Pro analysis tools.  BUT, then it occurred to me that this was actually a blessing for this activity, because the students actually had to decide what information was needed and grab the important times and velocities from the v-t graph (I told them they could check it using the x-t graph but they still had to show the work from the v-t) …not just use the Integral feature.

Here is what it looks like on the student screen:

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and now a close up:

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It was so easy to set up and the students really liked having the graphs right in front of them.  I loved that they had to determine what data to gather rather than one group asking for the data and then the others just using it.

I definitely need to play with all these features more.

So yeah, the Data Sharing ROCKS, thanks Vernier! And yeah,   I WANT MORE LABQUEST 2’S.

General Physics:

We WB’ed the mirror experiment and the students now see that the Thin Lens equation is actually he Thin Lens/Mirror Equation.  It was pretty cool to see that they could make use of another experiment from their journal to complete this activity.  Tomorrow we WB a few curved mirror problem.

 

By the way… DID I TELL YOU THAT VERNIER DATA SHARE ROCKS?