EXAMPLES IN CONTEXT
The following examples in context are sourced from the Australian Senior Secondary Curriculum: Physics. These examples have been selected to support the Science Understanding content of this course, and may be used to explore Science as a Human Endeavour concepts. The list provides a range of contexts in which the physics content related to Criteria 5, 6, 7 and 8 might also be applied to the impact of physics in society (Criterion 4).
The examples in context listed should not be taken as an exhaustive list, nor is it intended that all examples be explicitly taught. The examples are support materials and may be used to inspire assessment tasks, augment classroom teaching, stimulate discussion, or to simply act as exemplars for teachers.
Possible internal assessment tasks (based on the following or other relevant examples) may include written reports, essays, case studies, portfolios, scientific poster presentations, oral presentations and debates. Principles and concepts in the examples that are not part of Science Understanding content of this course will not be examined externally.
Forensic science – projectiles, C5 & C4
Ballistics is the study of the flight of projectiles, especially bullets. The path of a bullet can be predicted by understanding the effects of air resistance and gravity, and by determining the effect of environmental conditions. Scientists study and record the motion of bullets through use of analytical methods such as high-speed video analysis and 3D computer modelling. Databases have been created recording the motion of a variety of bullets from different weapons and computer matching is used to identify weapons used in crimes. Forensic evidence is often used in court though, despite messages in the popular media, forensic science cannot always provide sufficient conclusive evidence to lead to convictions.
Artificial satellites, C5 & C4
Artificial satellites are used for communication, research and observation. Knowledge of orbital heights and speeds allow satellites to be best positioned for observation of weather, natural phenomena, traffic and military movements. Communication via satellite is now used in GPS, satellite phones and television. Orbits and uses of satellites are classified by altitude (Low Earth, Medium Earth or High Earth) and by inclination (equatorial, polar, polar sun-synchronous). Thousands of decommissioned satellites, spent rocket stages and fragments from collisions (collectively called space debris) continue to orbit Earth, causing problems upon collision with functional satellites and posing danger upon re-entry into Earth’s atmosphere. Various strategies including active removal are in place to try to limit an increase in orbiting debris.
Developing understanding of planetary motion, C5 & C4
Ptolemaic astronomy proposed a geocentric model of the solar system that used the idea of epicycles to explain planetary movement. This model was used until Copernicus proposed a heliocentric model of the solar system that was later championed by Galileo, causing conflict with the Catholic Church. Johannes Kepler proposed three laws of planetary motion that form the basis of our modern understanding of orbits. Newton was able to show how these laws were derived from his theory of gravitation.
Medical imaging, C6 & C4
Magnetic Resonance Imaging (MRI) uses the property of nuclear magnetic resonance (NMR) to magnetise nuclei inside the body and create clear and accurate images of internal structures. MRI has many advantages over other imaging techniques such as computed tomography (CT) scans and X-rays, including greater contrast between soft tissues and an ability to take images without the use of ionising radiation. Due to the strong magnetic fields used in these machines, there are many safety procedures that must be followed and the procedure is often unsuitable for people with metallic implants or possible allergies to the contrast agents used.
Superconductivity, C6 & C4
Superconductivity is the phenomena observed when certain materials are cooled below a characteristic temperature, and zero electrical resistance occurs. Superconductors also exhibit the Meissner effect, where all magnetic flux inside is cancelled. Superconductivity was discovered in 1911 when the resistance of mercury was found to drop to zero at very low temperatures. A series of discoveries caused a number of theories to be put forward to explain the phenomena, but it was not until the late 1950s that a complete atomic scale theory of superconductivity was proposed. Since then, the developments of high temperature superconductors and practical applications for them have been the focus of research. Superconductors are used in magnetic levitation, such as in maglev trains, mass spectrometers, and in magnetic imaging (MRI). An extremely powerful and large superconducting magnet has been built for use inside the Large Hadron Collider at CERN.
Development of the wave theory of light, C6, C7 & C4
In the late 17th century, Robert Hooke and Christiaan Huygens published early theories of light as a wave and around 1800 Thomas Young showed through experimentation that light passing through a double slit showed interference and thus wave properties. Young also developed principles of coherence and superposition of light. For many years, the presence of the luminiferous aether was proposed as the medium by which light is propagated, an idea that was later disproved by experiments such as the Michelson-Morley experiment. Later, in the 1860s, James Clerk Maxwell developed a theory of electromagnetism and showed that electromagnetic waves would travel through space at the speed of light, implying light was an electromagnetic wave.
Monitoring earthquakes and tsunamis, C7 & C4
Major catastrophes like the Japanese and Indian Ocean tsunamis and the Christchurch earthquakes have led to an increased need to monitor and record the plate movements that cause these phenomena. Various devices including seismographs and computer modelling are used to detect, determine the location of and predict effects of earthquakes and tsunamis. Knowledge of different types of waves and their motion through the ocean and the continents allows prediction of the possible extent of damage or the timing of a tsunami. Earthquake engineering aims to limit seismic risk through design and construction of structures that are better able to resist the effects of earthquakes. A variety of methods including damping and suspension have been developed to protect buildings.
Noise pollution and acoustic design, C7 & C4
Noise pollution comes from a variety of sources and is often amplified by walls, buildings and other built structures. Acoustical engineering, based on an understanding of the behaviour of sound waves, is used to reduce noise pollution. It focuses on absorbing sound waves or planning structures so that reflection and amplification does not occur. When new roads are built, consideration is given to noise barrier design, surface materials and speed control. Buildings can be designed to limit the noise that enters from outside sources like roadways and low flying aircraft. Noise mitigation is also achieved by using particular materials for insulation and designing both the interior and exterior to reflect sound in particular ways. Safety equipment such as ear protection is compulsory and extensively tested for use in industrial situations due to the possible health consequences of exposure to excessive noise.
Radioisotopes and radiometric dating, C8 & C4
Radiometric dating of materials utilises a variety of methods depending on the age of the substances to be dated. The presence of natural radioisotopes in materials such as carbon, uranium, potassium and argon and knowledge about their half-life and decay processes enables scientists to develop accurate geologic timescales and geologic history for particular regions. This information is used to inform study of events such as earthquakes and volcanic eruptions, and helps scientists to predict their behaviour based on past events. Dating of wood and carbon-based materials has also led to improvements in our understanding of more recent history through dating of preserved objects.
Harnessing nuclear power, C8 & C4
Knowledge of the process of nuclear fission has led to the ability to use nuclear power as a possible long term alternative to fossil fuel electricity generation. Nuclear power has been used very successfully to produce energy in many countries but has also caused significant harmful consequences in a number of specific instances. Analysis of health and environmental risks and weighing these against environmental and cost benefits is a scientific and political issue in Australia that has economic, cultural and ethical aspects. The management of nuclear waste is based on knowledge of the behaviour of radiation. Current proposals for waste storage in Australia attempt to address the unintended harmful consequences of the use of radioactive substances.
Nuclear fusion in stars, C8 & C4
Energy production in stars was attributed to gravity until knowledge of nuclear reactions enabled understanding of nuclear fusion. Almost all the energy used on Earth has its origin in the conversion of mass to energy that occurs when hydrogen nuclei fuse together to form helium in the core of the sun. According to the Big Bang Theory, all the elements heavier than helium have been created by fusion in stars. The study of nuclear fusion in the sun has produced insights into the formation and life cycle of stars. An unexpected consequence of early understanding of fusion in stars was its use to inform the development of thermonuclear weapons. Research is ongoing into the use of fusion as an alternative power source.
Development of the quantum model, C8 & C4
Max Planck and Einstein were the first to describe light and energy as being quantised, a finding that led to light being described as spatially quantised photons of energy. The Bohr model of the atom was built on this quantised description of light energy and Rutherford’s nuclear model. The Bohr model was a quantum-based modification to Rutherford’s model and was rapidly accepted due to its ability to explain the emission lines of atomic hydrogen. Prior to Bohr’s model, the Rydberg formula describing the wavelengths of spectral lines of many chemical elements was known but could not be explained. A more elaborate quantum mechanical model of the atom, however, was required to explain other observations made about atoms. The quantum mechanical model of the atom uses quantum theory and describes electron orbitals that can be used to calculate the probability of finding an electron at a specific point.
Black body radiation and the greenhouse effect, C8 & C4
All objects in the universe, including the sun and Earth, emit black body radiation. The natural temperature of Earth can be predicted using the Stefan-Boltzmann black body radiation equation that assumes there is a balance between incoming and outgoing radiation. The true temperature is significantly higher due to the absorption of emitted black body radiation from the surface by molecules in the atmosphere (the greenhouse effect). Models of Earth’s energy balance enable scientists to monitor changes in global temperature, assess the evidence for changes in climate due to the enhanced greenhouse effect, and evaluate the risk posed by anthropogenic climate change. Further development of models of Earth’s energy dynamics and climate change enables scientists to more accurately predict the scenarios that will result in global warming, the time frames involved, and the likely impacts of these changes.
Development of the special theory of relativity, C8 & C4
Many scientists, including Albert Michelson, Hendrik Lorentz and Henri Poincaré, contributed to the development of the special theory of relativity. Lorentz’s Transformation and his ideas about the aether initially explained the Doppler effect. They were improved upon by the next generation of scientists developing theories about electromagnetic mass and ideas about inertial frames of reference and relative motion. Albert Einstein’s work on special relativity built upon the work of scientists such as Maxwell and Lorentz, while subsequent studies by Max Planck, Hermann Minkowski and others led to the development of relativistic theories of gravitation, mass-energy equivalence and quantum field theory. The Michelson-Morley and Fizeau experiments provided evidence for the special theory of relativity.
Ring laser gyroscopes and navigation, C8 & C4
Ring laser gyroscopes (RLG) are inertial guidance systems that do not rely on signals from an external source but from instruments on board a moving object. RLGs use small differences in the time it takes light to travel around the ring in two directions, known as the Sagnac effect. RLGs have many advantages over other systems: they are highly accurate, have no moving parts, are compact and lightweight, and do not resist changes to their orientation (ACSPH122). RLGs are commonly used in aircraft for accurate navigation and have military applications in helicopters, ships, submarines and missiles.
Nuclear reactors, C8 & C4
Special relativity leads to the idea of mass-energy equivalence, which has been applied in nuclear fission reactors. Nuclear reactors are most commonly used for power generation, propulsion and scientific research. Research reactors have resulted in advances in areas such as medicine and materials testing and fabrication through provision of nuclear isotopes for industrial and medical applications. Although nuclear reactors provide a range of benefits, there is considerable public concern over safety and security issues (ACSPH124). Data from the nuclear industry indicates that nuclear power reactors pose an acceptable risk to public safety and that much has been done to limit that risk. However, other groups argue that such a risk is not acceptable, and, even if no accidents occur, storage of the radioactive waste produced from nuclear facilities remains a safety concern.
Evidence for the Higgs boson particle, C8 & C4
The Higgs boson particle was predicted in the early 1960s by the Standard Model of particle physics. Evidence for the Higgs boson particle would confirm the existence of the Higgs field and help to explain why fundamental particles have mass. Discovery of the particle would guide other theories and discoveries in this field, including validation of the Standard Model, and insights into cosmic inflation and the cosmological constant problem. Production of the Higgs boson requires an extremely powerful particle accelerator. The Large Hadron Collider at CERN was built to test particle physics theories, and specifically to try to produce and detect the Higgs boson particle. Since the commencement of its operation, previously unobserved particles have been produced and most recently a new particle has been observed that is consistent with the theorised Higgs boson particle.
Particle Accelerators, C8 & C4
Particle accelerators propel charged particles to high speeds using a combination of electric and magnetic fields. High-energy particle accelerators are used in particle physics research to create and observe particles. These machines have gradually increased in size, complexity and in their ability to accelerate particles to higher speeds, thus increasing scientists’ ability to observe new particles. More practical uses of particle accelerators include their use in production of radioisotopes for medical treatments and as synchrotron light sources. The construction of the Australian Synchrotron involved collaboration between Australian and New Zealand science organisations, state and federal governments and international organisations and committees including the International Science Advisory Committee and the International Machine Advisory Committee.
The Big Bang Theory, C8 & C4
The Big Bang Theory describes the early development of the universe including the formation of subatomic particles from energy and the subsequent formation of atomic nuclei. There is a variety of evidence that supports the Big Bang Theory including Cosmic Background Radiation, the abundance of light elements and the red shift of light from galaxies that obey Hubble’s Law. Alternate theories exist including the Steady State theory, but the Big Bang Theory is the most widely accepted theory today. There is opposition to this theory in both scientific and religious communities due to its inability to explain what came before the singularity and because it cannot explain all aspects of the universe as it exists today.
Use Of Calculator Policy 2017.pdf