Stellar Evolution – updated theories

“This graphic gives a summary of our best current understanding of the evolution of stars, showing their birth, middle age and eventual demise. The lowest mass stars are shown at the bottom and the highest mass stars at the top. The very top line is a new addition, compelled by the detection of SN 2006gy — one of the brightest stellar explosions ever recorded — that describes the evolution of the most massive stars in the universe. Observational evidence for the special type of explosion shown here — which is incredibly bright and obliterates the star rather than producing a black hole — was lacking until SN 2006gy was found.”

Image and text via the SETI Institute.

Check out the animation for SN 2006gy:

This star is thought to be 130-250 times the size of our sun and while the light from the explosion was seen in 2006, the star is located so far away that the explosion actually occurred 238 million years ago and only a few years ago managed to reach Earth.

Fractal Nature of Electricity

Check this out! 15,000 volts of electricity running through plywood.

Fractals appear in nature very often. The really interesting part of fractals is that one equation can produce so many similar – but different results. Check these out as well:

In clockwise order these are: Selenga River delta, human kidney angiogram, deciduous tree in winter and fractal image created from a ‘simple’ maths equation. (Image from the Facebook group Science is Awesome)

For more examples of fractals in nature have a look at this webpage.

Year 8 Forensic Science Camp

The 2013 Talented Students’ Forensic Science Camp is being held at Armidale school from April 16-20 and is one of the nation’s pre-eminent extension programs for Year 8 students. It offers challenging and hands-on experiences of scientific problem solving and a chance to work with talented students from all over Australia.

As compelling as CSI, NCIS, as challenging as The Mentalist and addictive as Law & Order, the camp brings the intrigue of crime solving to the fingertips of young Australians. No one can resist a ‘whodunit’ and that is what this Forensic Science Camp is all about. It’s fast and exciting with total immersion in the scientific and problem-solving process.

The camp is a five-day residential experience and was first run in 1994. It has since been featured in the ABC TV science program, Quantum. Last year, over 100 boys and girls, a mix of city and country students from both government and non-government schools, were selected from a large number of applicants from NSW, the ACT, Queensland and Victoria to participate in the camp.

For more information about this camp and the application process visit their website and contact Mr R Jackson to obtain an information pack.

 

Applications now OPEN for Science Club 2013!

Applications are now open to join the 2013 science club at WCCS. This club is open to year 7 and 8 students who are interested in getting some more hands on experience with science. The aim of this group is to encourage students to develop a greater interest in and awareness of science and the amazing way our world works. We hope to bring back some of those old experiments from ‘the good old days’ that have left permanent inspiring marks on scientists around the world (and the roof of C3).

As part of this club we hope to encourage students to participate in some serious science. The club will aim to meet once a fortnight after school on a Wednesday from 3:15 – 4:15pm. Students will need to be picked up from school at this time.

Through this club we want to teach students that the cool stuff in science doesn’t solely reside in explosives and other pyrotechnics but that amazing and strange phenomena lie within all branches of science (though explosions are cool). Some areas that will be explored throughout the course of the year are:

  • Environmental Science (movement of the earth’s crust; volcanoes; effects of atmospheric pressure)
  • Biology (dissections; DNA examination)
  • Chemistry (Crystal formation; forensics; chemical based colour changes)
  • Physics (nature of soundwaves; explosives; forces and energy)

Term 4 will be a time for the students to show their true colours as we participate in the CSIRO Creativity in Science and Technology (CREST) Awards. This award is designed to help students develop skills in scientific research and inspire students to take up further studies in science.  CREST is a non-competitive science and technology award program for primary and secondary students and provides an excellent experience for training students in scientific investigation skills. As a result of completing the award students are awarded an accredited certificate from CSIRO as a record of their achievement. Completion of the CREST award will require some work from the students at home over term four, but support feedback and lots of time will be given during our regular meetings to assist students.

Entry into this club is by application as space is limited. Applications are judged on maturity of the student, demonstrated safety in a science lab, level of interest and achievement in science.  All students who have an interest in science are encouraged to apply to join this group. Students have until the end of week seven (15th March) to submit their completed application forms.

As this group is an extra-curricular activity the cost of chemical supplies will need to be covered by students. If you are offered a position in the group a $20 membership fee is required to secure your position. This money will cover all chemical and equipment costs for our regular meetings for 2013 and the registration fee for entry into the CREST program.

Please complete the application form (here) and submit to Mr R Jackson if you’re interested in this exciting opportunity by Friday week seven! Feel free to email us and ask any questions to either Mr R Jackson (jacksonr@wccs.nsw.edu.au) or Miss J Snelson who will be assisting us this year (snelsonj@willcarey.nsw.edu.au).

 

Spiderman Physics!

Physics students have recently proven that a correctly designed spider web could indeed stop a train travelling at high speed! Inspired by Spiderman 2 these students wanted to test the impossible seeming scenario where spiderman uses multiple spider webs to stop the train from plummeting off the track. Instead they’ve found that a single web would be sufficient to stop a full train at high velocity!

Spider silk has long been known to be one of the strongest materials around – much stronger than steel and Kevlar (the material in bullet-proof vests).

You can find the original article here

Pyrotechnic Delight!

Fireworks have many important components that come together to create the amazing effects we enjoy. To examine these components in detail we had an extended Science Club session this week.

Our first set of experiments was investigating how fireworks produce the colours that they do. Fire is actually a chemical reaction called combustion that gives off light and heat. So when we see burning wood, we’re actually seeing the light that is given off by hot gases reacting as they are boiled out of the wood. The colour of flames depends on the chemicals that are in the material being burnt. We made flammable mixtures of various salts. A salt is a simple chemical with a metal and non-metal bound together. Table salt (Sodium Chloride) is a very common salt, but is not the only kind of salt. While examining the coloured fire produced from different types of salt we were able to discover it was the metal component of the salt that determines the colour of the flame. For example, Sodium-based salts produce a strong yellow flame, Boron produced a bright green flame, Strontium was crimson red. Therefore, when we see wood burning yellow, we can conclude that it must contain Sodium-based salts (which is correct as most living tissue is rich in Sodium Chloride). Forensic scientists can use techniques based on this science to identify unknown chemicals. Pyrotechnicians use this science to mix chemicals to produce the brilliant colours in fireworks.

Combustion is a chemical reaction between a fuel and Oxygen (or more accurately, any oxidant) that produces heat and light. An explosive reaction is a sub-category of combustion reactions that occur fast enough to produce a sudden and large amount of pressure that expands outwards. We can hear this sudden change in pressure as sound. We explored the importance of Oxygen for explosive reactions in a series of reactions. Firstly we examined three balloons, one filled with Oxygen gas, one with Acetylene gas and the third with a mixture of both Oxygen and Acetylene. When we ignited the first balloon it didn’t react at all, there was no fuel and so the Oxygen merely floated away. The second balloon had plenty of fuel, but no Oxygen. However, when ignited it still reacted, as when the balloon popped the fuel could react with some of the Oxygen in the air. There wasn’t much Oxygen immediately available though and so not all of the fuel reacted. This ‘partial combustion’ produces a lot of sooty remains. The last balloon had a good mixture of Oxygen and fuel so when it was ignited all of the Acetylene reacted at once and produced a very loud explosion with no sooty remains. We demonstrated this concept again with Hydrogen gas in a Milo tin and blew the lid over the tree tops. Black powder (gun powder) and flash powder are two common explosive mixtures that rely on oxidizer-fuel reactions.

Fireworks though don’t use gaseous chemicals for their reactions. Instead they use various mixtures of powders. One powder is almost always a metal powder, this acts as the fuel for the reaction and provides the colours for the fireworks. The second powder typically contains Oxygen that is bound to other chemicals so that it stays a solid. There are many solid compounds that contain Oxygen, the ones used in fireworks are often Nitrates (the suffix ‘-ates’ tells us that this compound contains Oxygen) which is NO3. When they react the Oxygen leaves the Nitrogen and reacts with the fuel.

To demonstrate the explosive nature of some powders we produced Touch Powder. Touch powder is a solid compound of Nitrogen Tri-Iodide that can be triggered to explode by loud noises, small amounts of friction, heat from the air or even the soft touch of a feather. This compound is so easily detonated that even the Army won’t use it as the compound would explode if you tried to transport it anywhere – hence this explosive is classed as ‘sensitive’. This chemical reaction is actually quite different the typical reactions for fireworks and is NOT a combustion reaction. Instead, it is a decomposition:

2 NI3 (s) → N2 (g) + 3 I2 (g)

The Nitrogen Tri-Iodide literally blows apart producing very large amounts of gas. By rapidly producing large amounts of gas it produces a sudden increase in pressure and this is why we hear a loud explosion. Thus decomposition is a second reaction that can produce explosions (TNT, Nitroglycerin, C4 and RDX are common explosive materials that rely on decomposition reactions).
 

Here’s what we did:

Nitrate Flash and Pyrotechnics round #1

Redox reactions are the most important type of chemical reactions in pyrotechnics. Redox reactions are all about moving electrons that are fixed around one chemical to a different chemical – chemistry is all about understanding this ‘dance’ of electrons.

This week we examined one reaction in detail: The redox reaction is commonly called refered to as ‘Nitrate Flash’. Ammonium Nitrate was our ‘oxidiser’ it is strong enough to take electrons out of other chemicals. Zinc powder was the reducer, it gave up electrons to the oxidiser. The whole dance of electrons resulted in us producing Zinc Oxide, Nitrogen gas and water in the following net chemical equation:

Zn(s) + NH4NO3(s) → N2(g) + ZnO(s) + 2 H2O(g)

Notice the sub script (g) on the water molecule, that tells us that the reaction gave off enough heat to boil the water – so we actually made water in a gaseous state i.e. steam. Steam was the main gas you could see coming out of the reaction as Nitrogen gas is colourless (it makes up 78% of the air we breathe).

Notice though that in the ‘net’ chemical reaction we haven’t mentioned the water we added to start the reaction, or the Ammonium Chloride that was also included… they have a very special role called a ‘catalyst’ – look it up if you want to know more!

Here’s what we did:

To answer the question during the video, yes we did manage to set off the internal fire alarms :).

We managed to break the bin…