## Archive for February 2008

### Prefixes, Power & Precision

February 23, 2008

Millions and Billions, thousandths and trillionths. Numbers and more numbers. Physics is the study of the natural (physical) world, and as such uses many measurements, or constants. From the speed of light to the charge on an electron (elementary charge), From the mass of a proton to the radius of the sun, the parade of numbers marches on. The size of universe is incomprehensibly enormous (the macroscopic) and, paradoxically, reliant on the vanishingly small (the quantum):

These numbers can be gigantic or lilliputian, and to write them out in full (where possible) is an exhausting, and in some cases futile or even impossible endeavour. Nonetheless, we must have a way of writing them in sufficient accuracy. One way of doing this is to use scientific notation, by expressing the leading digits multiplied by the a power of ten. Here is a link to good explanation of how to work with scientific notation.

### Testing Times (part 1)

February 22, 2008

Tests are everywhere. Tests are more than “just” a part of school. You will be tested throughout your life – anytime somebody wants to know whether you know what you should know – or how well you know what you know – there will be a test. This could be your teacher testing what you have learnt, your boss checking to see if you can do the job right, or anybody who has responsibility for or authority over you. This is not a reason to be worried.If tests are going to be an ongoing part of your future, you have to learn how to deal with them. Here’s an example of what not to do: [kml_flashembed movie="http://www.youtube.com/v/m-W3D5saBFk" width="425" height="350" wmode="transparent" /]

The most important thing to remember is that a test is more than an assessment of what you know, it is an opportunity to learn in itself. If you treat a test as a learning opportunity it can make you far more successful in the assessment! So what’s the first step in this process? Easy:

### Total Talent Tryout!

February 22, 2008

Science can be as much of an art as a knowledge – it requires talented creative and imaginitive people at least as much as it needs the knowledgeable and intelligent. Better yet are those that combine all of these traits. The Science Talent Search is run by the Science Victoria, and has been run for 56 years. Competing in the STS is a great way to try out that idea you have always wondered about – perhaps you have always wanted to find out exactly how far a frisbee can be thrown…

### Doubt – the most important thought process

February 10, 2008

So why should you study Science? Some of you will say because you want a career in science, some because you think it will help you achieve your other goals. Some of you don’t want to study science at all, and will stop as soon as you can. Any of these reasons are insufficient.

You should study science for the same reason that you need make sure you have a healthy diet, or to have your vitamins. Science is necessary to fortify your mind, just as vitamins fortify your body. Your body is continuously exposed to various attacks – viruses and infections, injuries and stresses. You protect your body by avoiding threats, and healing injuries. Your mind is also continuously attacked by bad information, confusing memes and outright deceptions – Science helps to provide immunisation against these threats to your mind, and just as you use vitamins (from fresh food or artificial sources such as pills) to protect your body.

Dihydrogen Monoxide is a common chemical that you are exposed to every day. There are a number of dramatic effects as shown in the above link (read the Environmental effects statement), and petitions have been raised to ban it. This is unfortunate, as the following video illustrates:

### Re-Venn-ge

February 9, 2008

Sets are a powerful tool that allow us to look at groups of items instead of dealing with each item individually. By recognising some common property of a group of items, we can define them as a set, for example all left-handed, red-headed spanish plumbers could be used as a set. Not all members of the set would be identical in all ways – they could for example be male or female – but they would all be left-handed, red-headed and spanish. We use a specific set of symbols to work with sets, just as we use a particular set of symbols to write english. The “language” of sets is very precise, and you must ensure that you use it correctly. Here are two links (1, 2) to pages that give clear instructions on set notation (the symbols used for working with sets).While working with sets algebraically, using set notation, is very powerful, it is not particularly easy to “see” what is happening sometimes. For this, we turn to Venn Diagrams. Venn diagrams are named for John Venn, a 19th century logician and philospher. Venn Diagrams are a visual representation (a picture) of what is shown in a set notation statement. Venn Diagrams are very useful because they are a shortcut; they make a set statement clear and immediately relevant. You will need to recognise four main areas in a (2 set) Venn Diagram:

### Don’t worry, it’s just a fast (oxidisation) reaction…

February 5, 2008

Every explosion is “just” a reaction, admittedly one that progresses very quickly (Boom! Kaboom!). Oxidisation is the word used in chemistry to mean “a reaction with oxygen”. Oxidation reactions are essential because they release energy – respiration is an oxidation reaction, as is burning (combustion) and also corrosion. Respiration is good, burning can be good, and corrosion is rarely good. An example of corrosion is iron (Fe) rusting. When Iron combines with oxygen and water, iron oxide is produced:

4 Fe(s) + 3 O2 (g) + 2 H2O (l) → 2 Fe2O3·H2O

The reactants (Iron, Oxygen, and Water) combine chemically to make saturated (·H2O) iron oxide (Fe2O3). Iron oxide has none of the properties that are desirable in alloys of iron – it has low strength, is friable (crumbly) and completely non conductive. We try and prevent corrosion at all times, because it degrades materials. the two most common ways of preventing corrosion are:

1. Painting: The paint provides a protective layer that keeps the water/ oxygen from coming into contact with the iron. This stops the iron from contacting either water or oxygen, thus preventing the corrosion reaction.
2. Sacrificial Protection: This works by coating one metal by another. The coating metal must be higher on the activity series than the coated metal. One example of this is coating Iron with Zinc (also called galvanisation). This prevents the coated metal from corroding by causing the more reactive metal to corrode first.

The activity series shows some metals are more active than others – here is a video that shows how reactive (explosive!) some metals can be:

### Is it a bird? Is it a plane? Is it a wave! No! It’s SUPERPOSITION!

February 5, 2008

We have begun our studies of waves by looking at the various types of waves: longitudinal, transverse and torsional (twisting). We have also looked at the common properties of all waves. We have also looked at the definition of a wave, as a way of transferring energy without the transfer of mass. We have also begun to look at what happens when waves interact with each other. The following video is a look at what happens when many waves interfere constructively in a structure.