Gravity

In 1969, when humans first landed on the moon (on the Apollo 11 mission), one of the first things they did was drop a feather and a hammer to test which would hit the ground first. Why do you think they were interested?

• What happens when you drop a hammer and a feather (at the same time, from the same height) here on Earth?
• Is there any difference between performing the experiment on Earth and on the Moon?

Pre-Galileo
Did you hear the name that the astronaut mentioned? It was Galileo Galilei's. (Galileo was a physicist-astronomer who lived in Italy from 1564-1642.) For thousands of years before him, people believed that Gravity was a mysterious force that made things fall toward the Earth -- and they believed that the heavier the object, the faster it would fall. But Galileo changed everything.

Before we look at Galileo's theory, let's consider where the "old" belief about gravity came from. When you drop a hammer and a feather at the same time (here on Earth), the hammer will always land first. And if you try the experiment with all different kinds of things, this is pretty much always going to be the case for a heavy object and a lighter one: The heavier object tends to fall faster. Scientists observed this phenomenon for thousands of years and came to the conclusion that gravity affected heavier objects more than lighter ones.

However, they were not conducting their experiments on the Moon.

Galileo
Galileo (without ever leaving the Earth) did experiments many different objects that fell from many heights and rolled balls with different weights down inclined planes. Eventually, he came to the conclusion that gravity accelerates all objects at the same rate, regardless of their weight.

That means that even here on Earth, a hammer and a feather should land at the same time (like on the Moon). So why don't they? The answer: Air.


You know how when you ride a bike, you feel a breeze on your face (even when there's no wind that day)? The air is standing still, but you are moving, so it ends up feeling like there is wind pushing against the direction you're trying to go. It's the same principle with the hammer and the feather. A light breeze isn't going to push a hammer around, but it'll carry a feather away easily.

In the case of a hammer/feather drop, the breeze is trying to push each object in the opposite direction of the way they are falling (like the "wind" pushes against the direction you are trying to ride your bike). So even though Gravity is trying to accelerate both the hammer and feather at the same rate toward the Earth, the "wind" is blowing them in the other direction. On the Moon though, there's no air, so the hammer and feather can freely accelerate.

Peg Solitaire

I cannot stop playing this game!


A "European" Peg Solitaire board
Peg Solitaire is like one-player checkers: you jump pegs (or -- in the case of our board at Making Waves -- marbles) to take them off the board, with the objective of having a single peg/marble remaining.

Sounds fairly easy right? You'd be surprised. And once you've got the game beaten, you can try all different kinds of starting positions.

(I grew up playing a simplified version of Peg Solitaire at a restaurant called Cracker Barrel where they used to leave the game board out at the tables to play while you wait for your food.)

And for those of you feeling particularly Math-y, there are a couple pages out there detailing strategies and analysis of the board.

The European Union Has Already Developed a Plan to Stop Using Fossil Fuels for Electricity. Where's Ours?

It's called the Supergrid. The idea is a simple one:

Globally, the best renewable resource is solar energy. [...] Every year each square kilometre of hot deserts [in North Africa] receives solar energy equivalent to 1.5 million barrels of oil.
[...]
Solar factories can tap into this using concentrated solar power (CSP) plants [which] use mirrors to concentrate sunlight to create heat which is used to raise steam to drive steam turbines and electricity generators. An area of just 127km x 127km covered with CSP plants would produce as much electricity as Europe is using now.

Two German scientists, Dr Gerhard Knies and Dr Franz Trieb, calculate that just 0.5% of the world’s hot deserts, if covered with CSP plants, could generate as much electricity as the world now uses.

Okay. Pause for a second. The sun is burning millions of miles away from the Earth and just giving us its energy whether we like it or not. Before now, deserts were of use to very few living organisms. Humans have figured for the first time how to take advantage of these vast expanses.

Quick math:

• 1 sq. kilometer of the Sahara Desert receives as much energy (in the form of sunlight) in the course of a year as is contained in 1.5 million barrels of oil
• The Sahara Desert is about 9 million sq. kilometers
• 9,000,000 sq. kilometers X 1,500,000 barrels of oil per sq. kilometer = 13,500,000,000,000 barrels of oil

• Every year, the Sahara Desert receives sun-light energy that's the equivalent of 13.5 trillion barrels of oil
• FYI: That's way more than the 7.3 billion barrels of oil used every year in the US

The Supergrid itself is planned to be a web of High Voltage DC lines that stretch over thousands of miles -- at some points, even underwater. It would interconnect different areas of Europe and North Africa, and the majority of power would be supplied by solar energy from the Sahara, however every different geographic region in the web would contribute its own form of renewable energy (eg coastal countries would contribute energy from wind turbines).

What makes the Supergrid plan attractive is the use of 1) Concentrated Solar Power (CSP) plants to produce the energy and 2) DC lines to transport the energy.

Concentrated Solar Power
This refers to a way of converting sunlight into electricity by reflecting it off curved mirrors (parabolic mirrors to be precise) toward a liquid to heat it up and eventually boil water (which in turn spins turbines that make an electric current). It is a technology that is in its last stages of development and already produces more energy than other renewable sources.


DC Power Lines
I don't want to go too far into the difference between AC (Alternating Current) and DC (Direct Current) power, though you should know that (more or less) all power lines in the world are AC. (And I'd like to point out that when you plug an AC/DC converter into a wall socket, it takes the AC electricity from the power lines and converts it into DC electricity because for whatever reason your electronic device requires it.)

What's important for the Supergrid is that AC is works well for carrying electricity over distances that are less than a few hundred miles -- and therefore all the power lines in our country were built as AC -- however DC is better when you want to carry electricity over thousands of miles. That means, unfortunately that a whole new set of DC power lines will need to be built across Europe.

The plan has been proposed by a group called E-Parliament. Spain, Morocco, Algeria, and Egypt are already beginning to lay the groundwork, and there has been support from leaders in France, Germany, and the Netherlands. The former U.S. Vice President Al Gore has also spoken in support of the plan.

So where's the US's Supergrid?
Right now, there is one CSP plant in the United States -- called the Solar Energy Generating Systems (SEGS), which is in California's Mojave Desert. There used to be another one -- called Solar Two, also in the Mojave -- but it was shut down in 2001. The vast majority of the US's electricity is produced by burning fossil fuels -- including coal, natural gas, and oil -- which produce tons of carbon emissions annually.

But there's still hope! Whenever you hear Obama talking about the need to update our nation's infrastructure, this is one of the things he's talking about. If America ever wants to employ a green system like the Supergrid, we need to build new power lines first. Then, in time, we may build larger and larger CSP plants that could power the whole US. We're on the cusp of a new world of energy.

Student Skills: Test-Taking

[Note: The links in this post go to helpful pages on each topic. Follow them!]

Before the Test
It almost goes without saying, but the first key to test-preparation is GENERAL ORGANIZATION. Time management -- and the development of your REVIEW TOOLS -- over the days and weeks ahead of a test is probably the most effective boost to both your grade and your test-taking confidence. Once you've gotten into a groove with your classes and have a feel for the teacher, you can even begin to ANTICIPATE TEST CONTENT.

Testing Well
When you sit down to a test, you want to be in an optimal state to retrieve information that's been stored away in your head for the past couple weeks. Studying helps, but on test day, it's all about your brain. This means getting your body and mind into a balanced state.

It starts with studying enough to be confident in the material (none of that TESTING ANXIETY) and even arriving early to the test but also doing things to keep your body on an even level: exercising in the days before the test, eating breakfast the day of, deep breathing/relaxing if you even start to feel overwhelmed by the test. If you can do these, then strategic TEST TAKING will be like second nature for you (especially on MATH TESTS).

Having a LUCKY MASCOT when you study and take the test doesn't hurt either.

Cramming
Cramming for a test is pretty much incompatible with a healthy state of mind for test-taking, however it is almost certain that you will have to do it at some point. (That's why I figure it's better to mention it than to pretend that it will never happen.)

If you do hit a time crunch there are a few thing that you can do as EMERGENCY TEST PREP: You have to start by trusting what you already know of the material and identify 3-5 main concepts that have come up in your class. Write them, along with a brief description of each -- then compare that description with your notes and textbook. This will help you to figure which concepts you have a firm grasp of and which you need to work on.

After the test you crammed for, of course, it will be time to work on your TIME MANAGEMENT.

Mid-Terms, Final Exams
The STRATEGY FOR EXAMS is kind of a combination of all of the suggestions above. It's about Time Management (starting about two weeks before the exam), eating healthy and exercising (even though you've got a time crunch since finals are coming up!), Test Preparation, and Testing Strategy.

Don't worry. You'll do fine.

Corn-Based Plastic

[Attention: The proper way to dispose of corn-based plastic products is in your green, curbside-pickup compost bin (or a compost heap if you have one in your back yard). If neither of these are options, then put them in a garbage can, rather than recycling bin.]

• In 2007, Americans produced 256 million tons of trash
• 31 million tons of it were plastic
  • Only 2.1 million tons of plastic were able to be recycled; the rest went to landfills

As people are trying to become more green and cut down on their waste, scientists around the world are trying to find ways to cut down on the amount of plastic that goes into landfills. (You may have heard the pseudo-fact that plastic bags take 500 years to decompose.) One promising way to go about this is by developing biodegradable plastics (plastics that break down easily in natural settings -- like a log decomposing in a forest).

What's the problem with the "old" plastic?
The traditional plastics that you and I are used to are developed from fossil fuels (ie oil). This means that there are a great deal of carbon emissions (aka "Greenhouse Gases") from extracting the oil from underground and processing it into plastic. Also, as the oil-based plastic breaks down (over those "500 years" in the landfill), they will continue to release Carbon Dioxide (aka CO₂; aka the main man-made Greenhouse Gas). And this all on top of the space that plastics take up in landfills.

To avoid all these greenhouse gases (and save on rising oil costs), scientists and companies are now developing new types of plastic -- made from things beside oil -- that can biodegrade quickly and without all the Carbon Dioxide. Many different plants are being examined for their potential to be made into plastics (I recently heard about grass-based plastics). In the United States, we grow a crazy amount of corn, and it's rapidly becoming the popular new plastic. (So far, I've especially seen them as disposable utensils and clear, thin cups.)


If it's made from corn, it's "green" right?
The good news about corn-based plastics is that they cause far less Carbon Dioxide to be released into the atmosphere. Heck, the plastic originates from a plant that takes Carbon Dioxide and converts it into Oxygen. (Remember photosynthesis from your Biology class?) Unfortunately, not all of the Carbon Emissions of traditional plastics can be avoided: many of the power plants that run the corn-plastic factories are still burning fossil fuels like coal.

The bad news is that even though this new type of plastic can biodegrade (as opposed to the oil-based plastic), it only does so under very specific circumstances. The temperature must be about 140 degrees, it must be in a Nitrogen-rich environment, and there must be decomposing matter surrounding it. (Burying your corn-plastic fork in the back yard is not enough! You need a compost pile.)

This means that if you toss a corn-plastic fork into a landfill, it will still sit for 500 years next to that oil-plastic bag. And if you try to recycle it, it will just contaminate the oil-plastic that our recycling system is designed for. (The recycling system, of course, can be changed if corn-plastics ever become very common, but it will be expensive and take time.) Fortunately, here in the East Bay, we have an excellent curbside-pickup compost system, in addition to recycling and garbage. That is where the corn-plastic you use needs to be thrown out.

Also, it should be noted that corn-plastics are not as strong as oil-plastics. (As I mentioned above, they are considered a "contaminant" when they mix in with oil-plastics at recycling facilities because they make the oil-plastic weaker.) At cool temperatures, both plastics have about the same strength, but corn-plastic starts to melt at a significantly lower temperature than oil-plastic. This means that on a day where the temperature gets above 100 degrees, leaving corn-plastics out in the sun is a very bad idea. Not only because the plastics become weaker, but because they are toxic to humans and may contaminate any food or water that they come in contact with. (Think about water bottles that sit for a couple hours by the benches at a baseball field.)

Just tell me already: Are corn-based plastics good or bad?
If you have a green curbside-pickup bin or a compost pile in your back yard, then by all means go for the corn-plastics. (If you don't, then the decision can be a little tougher.) I'll say this much: even though they're not perfect yet, alternatives to oil-based plastics are definitely a good thing. Right away, the corn-plastics can reduce the amount of Carbon Dioxide we produce. And in the coming years, we may find plastics developed from other plants that are less toxic as well (oil-plastics are toxic enough as it is).

What does "overweight" really mean, anyway?

Just this morning, I went to see a new doctor. As part of all the procedures that we went through, she weighed me and measured my height. I knew what dastardly tricks she was up to: My doctor was calculating something called my BMI -- short for "Body Mass Index." It's a very simple method of classifying people's body-types, typically used to determine possible health risks. Essentially, you take a person's weight and divide it by their height squared.

(Okay, it's slightly more complicated than that because you need to have the weight in kilograms and the height in meters, instead of pounds and feet like we use in America. Fortunately, some easy multiplication can change our units of measurement into the correct form.)

The formula for BMI is:

So, you take a person's weight (in pounds) and multiply it by 703. Then, divide that product by the person's height (in inches), squared.

This may seem confusing so far, but let's think about what the BMI is figuring out. It's looking at two things: weight and height. Where have you seen a height squared before? (Phrased differently: What happens when you multiply a length times itself?)

Area=a²
The Area of a Square is found as the length of one side squared. This is just like what the BMI tells us to do with a person's height: Mathematically, the BMI flattens and stretches out a human body into a square that's as tall and wide as the person's height.

But overall, BMI is the person's weight divided by the person's height squared. So what does that mean? Basically, it determines how heavy each little square inch of the person's flattened out body is; it's some number of pounds per square inch (Rather it's the number of kilograms per square meter).

Okay. Now that we know how to figure out a person's BMI, let's calculate one real quick: mine. As of this morning, I am:

• 5'9.5"= (5 feet X 12 inches) + 9.5 inches = 60 inches + 9.5 inches = 69.5 inches
• 193 pounds

So,

• We square my height:
• (69.5 inches)²=4830 inches²
• Read aloud, that's: "Four thousand, eight hundred and thirty Square Inches"
• And divide my weight (times that conversion factor) by the height squared:
• (193 pounds X 703)/4830 square inches = 28

But what the heck does "28" even mean?

The World Health Organization has a handy chart that it gives to doctors around the planet to figure out health risks for patients based on their BMI:

BMI	Classification
Less than 18.5	Underweight
18.5–24.9	"Normal" Weight
25.0–29.9	Overweight
30.0–34.9	Class I Obesity
35.0–39.9	Class II Obesity
Over 40.0	Class III Obesity

So, according to the WHO, I am Overweight. This basically means that I have a slightly increased risk for certain types of cancer and possible heart problems over people who have a "Normal" BMI. This is where the problems start.

For a person with my height to have a "Normal" BMI, I would have to weigh somewhere between 127 and 172 pounds. I'll admit, if I lost 20 pounds, I'd be a little better off -- although I'd be skinnier than looks healthy for someone with my frame. According to the BMI, however, 172 pounds is supposed to be my maximum weight. They're saying that I could even weigh down to 127 pounds and be "Normal." If I weighed 127 pounds, I would be a sickly little thing that gets blown around by the wind. Even my doctor would tell me to gain a little weight.

All types of groups are against the BMI system for various reasons: 1) It identifies one group of people as Normal... which implies that people outside of that group are Abnormal. 2) The "Normal" group isn't necessarily the healthiest for many reasons, including the fact that 3) it doesn't take into account much human variation.

(I'd like to point out, specifically: studies have shown that people in the "Overweight" and some in the "Obese I" range of the BMI have the lowest risk for some types of heart disease.)

There are much better systems out there, including the Waist-Hip Ratio. This system is also pretty easy to compute: Divide the length around of your waist -- up near your belly-button -- by the length around of your hips. Females should shoot for the ratio 0.7-0.8, and for males, the ratio should be 0.9-0.95. These are only rough figures, since more research still needs to be done. But, in fact, a new study just came out confirming that Waist-Hip Ratio is better as a health indicator than BMI. (They examined 359,387 different people and came to that conclusion!)

As my doctor weighed me this morning, I told her that I don't buy the BMI system and that I believe there are better ones out there. She responded: "Then, I won't tell you that you should lose a couple pounds."

Student Skills: Classroom Participation

[Note: The links in this post go to helpful pages on each topic. Follow them!]

The classroom is the space in which a teacher gets all their impressions of you. The first thing that has to be said is PAY ATTENTION! (The only way that I can ever pay attention is if I'm in the first row of the classroom. Any further than the second row, and my mind will be all over the place.) And why pay attention? So you'll be great at TAKING NOTES, of course. There are many different strategies for note-taking, but sometimes, it's important just to jot down a few of the buzzwords your teacher throws out. Knowing what strategy to use totally depends on the class and how much you think you need to work to retain the information.

There are also the ever important CLASSROOM DISCUSSIONS where you get to demonstrate your intellectual prowess and show a teacher what you're all about. Even if "Classroom Participation" is officially only a small part of your grade, performing well can make things in the class run a little more smoothly. In fact, there are lots of little things that you can do to INFLUENCE TEACHERS that will make them believe you are the most interested student in the class (even if it's not exactly true).

Heck, a teacher's high opinion of you might even translate into things like a little boost if you're on the borderline between a B+ and an A- or that extra day you need to finish an essay.

A New Particle?

Back in September, you probably heard about that new particle accelerator in Europe that lots of (uninformed) people believed was going to end the world. Well, it kind of broke down before we had the opportunity to accidentally make black holes that would swallow us up. (Actually the way it broke and needs to be fixed is kind of cool: the accelerator runs at about -450 degrees Farenheit and needs to be warmed up so people can go in the room to fix it.)

In a way though, that breakdown is good news for us, since that means that the United States' old particle accelerator is still the most powerful in the world (until next spring when the European one is fixed). And on top of all this our old busted particle accelerator may have DISCOVERED A NEW PARTICLE! There were no predictions about its existence -- though one of the lead scientists on the project thinks it might be related to a developing theory of dark matter.

The suggestion of a new particle is actually really controversial; it may well turn out that it was an old particle doing some new tricks for us. In fact, nearly a third of the scientists working on the project don't want their names included in an article that's coming out soon about their findings. It's way too early to know whether it was a new particle or some older one. Only time will tell.

[On a related note: Another group of scientists are searching for dark matter right now, deep in a mine in Minnesota. The article is really informative and can help you to understand what dark matter is all about.]

Playing with Functions

Comparing graphs of linear equations can be really helpful in trying to understand them, but just trying to graph them takes a really long time. Fortunately for us, someone out there wrote a Java applet (a simple program) just for us, called Slope Slider. The whole concept is that you can push the colored sliders left and right to easily change the slope and y-intercept.

The big questions to think about are:

• What happens to the slope when it's greater than 1 and getting bigger?
• What about the slope between 0 and 1?
• How different are the lines with slopes +10 and -10? What about +100 and -100?

[Note: When you're done with the "Slope Slider" check out this other applet that graphs functions for you. Typing in the function can be a little bit funky, since you have to use an asterisk (*) to do multiplication and a caret (^) to show that what follows is an exponent, but it can graph almost any function you want.]

Student Skills: Studying

[Note: The links in this post go to helpful pages on each topic. Follow them!]

Studying well doesn’t necessarily mean studying a lot; it means reading efficiently and being able to hold on to the information. Before anything happens you have to get in your zone. That means finding a space – both at a STUDY SPACE and in your head – where you can CONCENTRATE.

In that space, reading can be more like SKIMMING, instead of long and intensive. And I’ll give you a tip, there are tons of tricks to help MEMORIZE information, but the best way is to see it often. Instead of studying vocab for an hour the night before a quiz, try fifteen minutes a night for four nights; either way, it adds up to 60 minutes, but one will do you just a few points better.

And laid out in front of you, it often helps to see MULTIPLE SOURCES of information. A textbook has facts, but it can be dry…and limited. Maybe your teacher gave you a handout with a short story illustrating a point from the textbook or a class lecture that you surely still have the notes from. Heck, maybe someone made a youTube video out of that story. Getting a big picture can help hold together all the little details that you’re trying to memorize.

Student Skills: Time Management

[Note: The links in this post go to helpful pages on each topic. Follow them!]

The first thing that any student needs to do is get their PRIORITIES straight. But when you’re figuring them out, you have to be honest! You know plenty of kids who prioritize schoolwork over the rest of their lives – and that’s great, you get plenty of work done like that – but if you tend to take new MySpace pictures instead of practicing Spanish vocab, you have to start by admitting that it’s something important to you and that has to be in any schedule you make for yourself.

Schedules are really helpful to refer to both when you’ve got tons of work (and you need to figure out how you’ll fit it all in) and when your time can be more relaxed (which is when I tend to forget whatever is due). For Long Term planning, a WEEKLY SCHEDULE or MONTHLY CALENDAR to fill in are helpful – and the Weekly Schedule can help you find things like time slots to squeeze in a little extra review, during Exam Week. You probably know most of your usual DAILY SCHEDULE already, but writing it down can help you make your days more efficient.