Standard Grade

standard grade physics is in here

very large telescope

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I found a brilliant timelapse video on the Popular Science site.  It shows the Very Large Telescope (VLT) at work in Chile.

Here are some VLT links to explore

You can get a pdf summary of the VLT from the European Southern Observatory (ESO), the organisation that runs the VLT, by clicking on the download link below.

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Endeavour takes antimatter hunter to the space station

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image by NASA

A few weeks ago we were all ready to look up for an evening sighting of the space shuttle Endeavour as it separated from its external fuel tank while passing over the UK.  That launch was delayed but NASA is set to try again today.

Endeavour is the newest vehicle in the shuttle fleet.  It was built as a replacement for Challenger.  This will be Endeavour’s last mission and its task is to carry the Alpha Magnetic Spectrometer (AMS-02) up to the International Space Station.

Launch is scheduled for 1.56pm UK time and you can watch it live on NASA TV.  Alternatively, you can watch the launch as a webcast from CERN, starting at 1.45pm.

AMS is designed to search for antimatter, a substance first proposed by British Physicist Paul Dirac.

Physicists believe that there should be a balance between matter and antimatter .  The problem is that we live in a universe that seems to be made from matter, not matter and antimatter, so the question is…

where did all of the antimatter go?

Particle physicists at CERN’s Large Hadron Collider have an experiment that is looking for an answer to this question.  The particle physics research teams at CERN were given the job of building the AMS, which was transferred to the Kennedy Space Centre earlier this year.

The videos below are from CERN’s multimedia library for the AMS project and will give you an idea of the role of AMS.  The first film is less than one minute long and designed to act as a trailer for the project.  The second is longer (15 minutes) and has several interviews with key project staff.

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re-entering the earth’s atmosphere

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In space there is no air resistance to oppose motion, so the Space Shuttle orbiter can travel at very high speeds, up to 17,321 mph!  At these speeds, the orbiter experiences enormous air resistance as it descends into the Earth’s atmosphere at the end of its mission.

This air resistance is just like any other form of friction – it converts kinetic energy into heat energy.  The effect of this heat energy is demonstrated in this video clip taken by a Canadian police car camera.  It shows a meteor burning up in the atmosphere above Edmonton.

Thankfully most meteors do burn up in the atmosphere, although the dinosaurs were not so lucky.

The high temperatures created during re-entry ionise the gas around the orbiter and this is often seen as a bright light in NASA cockpit videos, such as the one shown below.

To protect the vehicle and its crew from these high temperatures, the underside of the orbiter is covered by a layer of heat resistant tiles called the thermal protection system.  This NASA clip explains how the tiles are constructed and arranged on the underside of the orbiter.

When Columbia was launched in 2003, something fell against the insulation on the left wing and knocked off some of the tiles.  This hole in the thermal protection system caused Columbia to explode over the US as it re-entered the atmosphere.  There is a wikipedia article about the Columbia disaster.

Video footage of NASA’s Houston control room from the morning of the disaster was included in the BBC Horizon documentary Final Descent – Last Flight of Space Shuttle Columbia.

WARNING: This last film is an excerpt from the Horizon programme and includes genuine cockpit video that was found in the wreckage, with some clips of the crew’s final minutes before they were killed.

There is a good description of the Space Shuttle at How Stuff Works.

star classification

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We know that our sun is a fairly common star.  In fact, the fanciest thing about our sun is probably the fact that the 3rd planet (Earth) in its solar system has life!

In this video, astronomers talk about how they can use the line spectra from stars to classify them into different categories.

electric motors

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image by explainthatstuff

We’re finishing off the electricity unit by looking at electric motors.  The page I used in class to help explain how a simple electric motor works is available here.

Here is another nice animation that shows the key parts of an electric motor.  It will stop after a few rotations but just reload the page to see it again.

Real electric motors have a few modifications;

  • they use field coils instead of a bar magnet – the field coils form a strong electromagnet when current passes through them.  The field coils do not rotate.
  • the single rotating coil is replaced by several rotating coils
  • there are more contacts on the commutator – each pair connects to a different rotating coil
  • the brushes are often made from carbon instead of metal – the carbon conducts electricity and can withstand high temperatures.  Carbon also moulds to the shape of the commutator to give a good electrical contact

image by marrrci

electrical wiring at home – the ring circuit

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Wikipedia has a good description of how a ring circuit is used in home wiring.  The diagram below is neater than the one I drew on my board in class.  You can click on it to view a larger version of the drawing.

drawing by Andrew C.
  • The ring circuit for power sockets is rated at 30A.
  • The ring design allows electricity to reach the socket from two different directions, so the current flowing in any one wire is lower.
  • Since the current is lower, a thinner cable can be used.  This saves money as copper is expensive.

Click below to download the Scout guide to home wiring.

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