Gary Garber's Blog

So this week, they awarded the Nobel Prize in Physics. David Wineland from U. Colorado received the prize for his work in Quantum Optics.   17 years ago when I was applying to grad school for Photonics programs, I was actually decided between Colorado, Arizona, and B.U.   That was just when Colorado was making a lot of its big optics discoveries.   No regrets.  Boston is more fun.

This week we have finished up Newton's Third Law.  After several probing questions about action-reaction, I posted the following question.

A robot pulls on a rope with a certain amount of tension T read by a scale.

Now two robots have a Tug-Of-War and pull on the rope from either side.  What is the reading on the scale.

a)   Zero

b)  Equal to the original Tension T

c)  Twice the original Tension T

This is a great question because the answer is not obvious.  The students then tested their ideas using the LEGO NXT robots.  Most houses used spring scales, but the ambitious Gryffindors went and connect Vernier Force Probes into NXT-Vernier adapters which allowed the robots to measure the tension in the string!

They wrote the above LabView code for this experiment.  Way cool!

Today the students measured the height of Marsh Chapel.  This was fun because there was so much variety in student methods.  Some students used trigonometry.  Some students used similar triangles.  Some students used image analysis.  Bravo for the students who helped each other out and worked together as a House to score lots of points.  Boo-hiss on those who could not cooperate.   They lost points.

But what surprised the students is how short March Chapel is.  There is an optical illusion.  Buildings are much taller than they seem.  Michael and Tom use a 45 degree angle to find the height of the chapel.  Which meant the chapel was only as tall as they were far away.  It wasn't as tall as they thought!

So today, the last group of students finished our experiments on Galileo.  The question we explored was the Law of Falling Bodies (objects that are falling continuously accelerate and the distance traveled depends on the square of the time) and whether or not the acceleration of a falling object depends on mass.  Some groups dropped objects, whereas others used ramps.  Some used ultrasonic motion sensors by Vernier.   Others made videos and used the Image Analysis software developed by Jessie Thorup, a recent graduate in mechanical engineering from Tufts.  The one interesting hiccup with the software is that it would download the data into a Google Docs.  But with the recent migration to Google Drive, she needs to update the software.

I was going to dive into vectors next, but rumor has it I might be getting a touch table from Templeman Automation the first week of October, so I decided to hold off until after Camp Wing.

After Monday's exam, we will be exploring the forces and accelerating motion.  We will finish our adventures with Galileo and the idea that objects of different masses will accelerate towards Earth at the same rate.  Hufflepuff already started to play with this, dropping bowling balls and LEGO balls.  Another group played with carts of various masses, and even a LEGO frictionless cart using the PASCO bearings.

From there we will explore accelerating systems with unequal forces, friction, and Newton's 3rd Law.  Then a brief break for for Camp Wing.

We had some great verbal discussion about velocity today.  What I thought were straight-forward homework questions turned out to present some deep conceptual misunderstandings.  We explored the definitions of displacement, velocity, and what the average in average velocity really means.  We began to play with carts accelerating down ramps.

Some parents wanted to know more about what we are doing and why, so I have posted the two recent papers we published last year.  One articles was presented at ASEE (American Society of Engineering Education) conference and the other at the IEEE conference.   These articles are rather technical so I will post some non-technical articles soon.

Today we programmed LEGO Mindstorm robots with LabView and designed an experiment to measure the speed of the robot.  As a note to parents, it is important for students to take the content learning seriously.  Many students were unprepared for today's class.  I might even suggest taking notes on the text readings, videos, or blog entries, the way one would for a lecture.  I might have to even require and check such notes.