So it has been a busy week in the lab. After cleaning up after our VEX Tournament on Sunday, the students have been busy building our FRC robot! They have been busy prototyping a few different ideas. You can read the updates here.
One of our alums, who was a freshman when during the first year I ran the robotics team almost about 13 years ago, Sam Duffley, finished building his robot as part of the Robot In 3 Days competition.
So check out the videos. These are FIRST alums who decided to see if they could build a robot in 72 hours. He is part of Team Boom Done, which is the iRobot team.
You can watch their team here.
By Gary Garber|Posted in Physics|Comments Off on Robot Season off and Running
The end of the semester was busy hosting a FIRST LEGO League tournament but things are finally now back up to speed.
We finished the semester studying projectiles and satellites. One famous physics demonstration in the study of projectiles is the Hunter Monkey demonstration. Stav produced a great slo-mo video of this demonstration I wanted to share. The physics question is, "A hunter aims his gun at a monkey in a tree. If they monkey lets go of the tree branch the instant it hears the gunshot, why does the projectile still hit the monkey?"
By Gary Garber|Posted in Physics|Comments Off on Projectiles and Winter Break recharge
This past week we started to study momentum, and how to give an object momentum by exerting a force over a period of time, or an impulse.
One demonstration the students enjoyed was throwing eggs at a sheet. Here we can see the students throwing an egg at a sheet, yet it is not breaking! The sheet extends the time of impact, thus lessening the force. Here you can see this is slow motion thanks to Stav and his iPhone. 10 points for Hufflepuff.
In the coming week, we will be examining collisions. In time for Halloween, I call this lab "Creepy Crawly Carts that go BUMP in the middle of the night." Some carts go BUMP and stick together with Velcro. Some carts are silent and make no noise when they collide (magnets). Other Creepy Crawly Carts go BOOM in the middle of the night. They 'explode' apart using a spring loaded plunger. Click here to view the lesson on these Creepy Crawly Carts.
Often students (in a panic) ask m if it is okay that they have not done their homework. I sometimes facetiously answer that the only thing that will prevent the asteroid from hitting the Earth is a completed homework assignment. Well, the asteroids have been in the news a lot recently.
To quote Craig Robinson, director of the Copernican Observatory and Planetarium at CCSU, "Speaking of asteroids hitting the Earth one of the largest, if not the largest found so far, fragment of the meteorite that landed in Russia this past February has been found in the lake next to the city it landed in. This particular fragment looked to be about the size of a desk and is roughly roundish in shape. They tried to weigh it but the scales they tried to weigh it on broke so at the time I saw the news cast about it (This morning.) there was no idea about its weight other than it was very heavy for its size."
Here is the CNN video on finding the piece at the bottom of the lake.
There was also a recent deluxe article on the asteroid on BU Today. Just how are we going to save the Earth from the asteroid, which has a LOT of momentum? Can we blow it up? Or do we nudge it slightly? Deliver an impulse with a laser beam? If we exert a small force (laser) over a long period of time, we can still deliver a significant impulse to the asteroid. Read what BU Professor West Jeffrey Hughes has to say on the subject. I think if we take all the uncompleted homework assignments from BUA students over the years, put them in a rocket, and launch it at the asteroid it might provide just enough impulse to push the asteroid off course and save the world! I should enter this idea into the NASA Grand Challenge.
By Gary Garber|Posted in Physics|Comments Off on Momentum and an asteroid hitting the Earth
Last week we finished our studies of Newton's Laws and started to explore motion in two dimensions.
In order to explore the ideas of Action-Reaction we had robots perform a tug-of-war. The question is, when is the tension greater. When a robot pulls on a rope tied to the wall, or when two robots pull against each other? This is based on a problem I call the Blind-folded-tug-of-war.
In a moment of frustration with the Ravenclaws, I decided they needed to be taught a lesson, grabbed some blindfolds (old concert T-shirts, Iron Maiden/Guns and Roses from 1988) and a long rope and we had a tug-of-war. Once again, try as hard as the boys could, they were not able to beat....the wall.
Here you can see the girls pulling on one end of the rope....and then
Here you can see the boys pulling on rope....thinking they were pulling the girls....but really pulling the wall. The tension is the same as the wall pulls back on the boys with an equal and opposite force. Actually this is an old photo.
It has been a difficult week as far as physics goes. Vectors and trigonometry can be a big challenge for many of the students. The big goal is to try and make sense of the incline plane problem to close the book on our study of Galileo. One can analyze this using trigonometry...of course, Galileo didn't use that. Interestingly, Galileo didn't even use algebra. All of his proofs were done using Euclidean Geometry...the old stuff. Not what we teach students in school today, but you would have to study the books of Euclid just to read what Galileo wrote. There is actually is a guy over at Harvard, Andy Engelward, who teaches a class for teachers on how to teach real Euclidean geometry. My wife took the class so I got to play around with her problem sets. You have to perform all the proofs using only a piece of string and a straight-edge. Good thing I am not teaching geometry here. That would be fun!
By Gary Garber|Posted in Physics|Comments Off on Newton’s 3rd Law and Vectors
Today we started class by discussing the Higgs Boson, which is particularly relevant since we are talking about Newton's Second Law. Perhaps someday, we will call it Newton's Model of Dynamics instead of Newton's Law.
As teachers we often engage in professional development. As my son Leonardo often asks, why do I need to go back to school. What grade am I in? Grade 100?
I went down to Cambridge to a program run by Blossoms. Blossoms is trying to integrate video into the classroom. Not in that 1980s way of TV in the classroom that put us all to sleep. But in our YouTube generation, with 2-5 minute video clips. The idea of Blossoms is to show students professionally made short video clips to inspire in-depth student explorations and discussions. What is particularly interesting about Blossoms is their international reach and how all their videos are translated into Arabic and Portuguese. The program is run by Richard Larson, who is the producer behind all of the famous Walter Lewin videos. So another new adventure! If you are not familiar with Walter Lewin, watch below.
By Gary Garber|Posted in Physics|Comments Off on Blossoms and I went back to school this weekend
The students just finished writing lab reports on Galileo and inertia. They worked hard this weekend exploring the ideas of why do all objects in free fall accelerate uniformly towards the Earth no matter what the mass. The short explanation is that as weight, or the force of gravity of an object increases, the inertia of the object increases proportionally, thus the acceleration due to gravity is uniform for all objects.
A question came up today, "what is inertia, is it a force?" Many of the students wrote this in the rough draft of their introductions, and I corrected them. Or they wrote it on their exams, and again I corrected them. According to our textbooks inertia is a property of matter which resists force. I briefly discussed this in a post in early September. What does this have to do with the Nobel Prize? Well there are many suggesting that Peter Higgs will get the prize. I watched this nice video from Nova last night. As you can read in my posting from about a year ago, the idea of the Higgs field is that the Higgs (inertia) causes a force that is proportional to acceleration. So even though all of our textbooks tells us that inertia is NOT a force, the recent discovery of the Higgs Boson might make us have to revise how we teach Newton's Laws.
F= ma
might take on a new meaning, where F is now the Higgs Force.
I imagine after I pass back their exams tomorrow, a few students will ask about their "wrong" answer where they called inertia a force. Ahh, but they didn't mention the Higgs.
By Gary Garber|Posted in Physics|Comments Off on Who will win the Nobel?
Great article last week on Phys.org about the Lycurgus Cup. This is a personal story that reminds me of my wife's wedding ring.
The Romans knew to spike the glass with a few hundred parts million of silver and gold in order to create a dichronic effect.
"The goblet was created approximately 1,600 years ago, using a process whereby very tiny gold and silver particles were embedded in the glass. In normal lighting, the glass appears to have a jade background. When lit from behind, however, the green parts suddenly look ruby red. This is all courtesy of the way electrons vibrate when struck by photons—something the Romans could not have known. Yet, because other goblet pieces have been found with the very same mixture, it's clear they knew they were on to something. They actually used the color changing effects to create stories. The Lycurgus Cup, for example, depicts the story of King Lycurgus as he is caught up in a tangle of grapevines—penance for treachery committed against Dionysus, the god of wine in Greek mythology.
Researchers speculate that the Romans simply ground the metal particles until it would take a thousand of them to match the size of single sand grain, then mixed them in with the hot liquid glass. But that wasn't the end of the story: the Romans created a goblet such as the Lycurgus Cup, by carving it from a single block. That means they also understood that different thicknesses of the glass would exhibit different coloring as well."
Back to me. Instead of buying my wife a diamond ring for our wedding, I got her an Alexandrite stone. However, Alexandrite is a chrysoberyl stone, which has some chromium mixed in to make it into a mood ring. Depending on the lighting, it is either green or red.
By Gary Garber|Posted in Physics|Comments Off on The Romans were experts in Nanotechnology!
For those of you who are physics teachers and AAPT members, please vote for Sam Sampiere for AAPT Vice-president. Sam currently runs the New York section and he gave an AMAZING demo show last year at the Regional NSTA meeting in Hartford.
And if you are a senior at Boston University Academy, you should vote for Daniel Gorelick for student council. (Thanks for the pizza).
A long drive back from the meeting. The view driving along the Salt Point Turnpike was amazing particularly driving through the Hamlet of Salt Point.
I loved looking at the train bridge crossing the Hudson in Poughkeepsie. No trains while I was there.
By Gary Garber|Posted in Physics|Comments Off on Northeast AAPT meeting, David Maiullo, and who you should vote for
