New trends in physics teaching, v.4; The ... - unesdoc - Unesco

New Trends in Physics Teaching IV
table (using stroboscopic pictures for evaluation), with vehicles on a linear air track (using photodiodes
and an electronic counter for measuring the time) or with trolleys on a low friction track
to which is applied a simple electrostatic method for time measurement (using powdered sulphur
and the mains supply).
The pupils are searching for conserved, unchanging quantities and so find the idea of momentum
(from which they get Newton’s second and third laws). In the case of elastic collisions, they
discover ‘the conservation of the square of the velocity’ of trolleys, and so get a feel for the
concept of kinetic energy. In the fourth year, the exercises introducing statistical physics begin
with the throwing of dice in a way which is rather similar to that described in the Nuffield
Advanced Physics Unit 9 (Change and Chance) [ I5 I . From statistical physics the Hungarian
curriculum goes on to use the energy point of view in both nuclear physics and astronomy, so
achieving a unity of pedagogical treatment. The extended use of a three-dimensional model
for the nuclear binding energy helps when considering the energy budget of the universe. This
model effectively demonstrates that during radioactive decay and during stellar evolution, the
cosmic matter ‘flows into the ferrum lake’ because the ‘energy valley’ around iron in the periodic
table is the deepest, so offering the most stable state.
CONCLUSION
In the last century physicists believed that school physics was a condensed form of complete
physics. The information explosion of the present century has rendered this belief pedagogically
absurd. One has to select a unifying standpoint from which one can educate students to
develop precise thinking about the world we live in. In the traditional school physics curriculum,
the favoured central concept was that of force (measured by springs). That concept has one great
disadvantage, however; in Physics, outside Newtonian mechanics, its value is low and it is almost
useless in modern chemistry and biology. The ‘chemical force’ (valence) and ‘vis vitalis’ mean
something completely different. So a force-centred physics curriculum results in the isolation of
our subject from the other sciences. The new Hungarian physics curriculum is energy-centred,
energy being taken to include internal energy and light energy from the very beginning. This
central role for energy places heavy emphasis on thermodynamics, electric energy transfer, the
ground states of atoms and crystals, stellar evolution and human energy resources; it opens doors
to chemistry, biology and economics. Using it, we shall be able to present physics as a subject of
real relevance to all men and women.
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