Physics KS3/4: Conservation of energy

Professor Brian Cox explains the first law of thermodynamics.

He describes how energy is always conserved, never created or destroyed.

He uses an analogy of a waterfall to explain how gravitational potential energy (for which he gives the formula) is converted into other forms.

He ends with the quote, “Every single joule of energy in the universe today was present at the Big Bang 13.7 billion years ago.”

This clip is from the series Wonders of Life.

Teacher Notes

Students could review the different types of energy and the conversions that occur between them. Can they identify the conversions involved in a hairdryer or toaster? The relationship between energy and work can then be covered.

Students can be asked why the units of both are joules. Rollercoaster rides are likely to be a useful example of how gravitational potential energy is converted to kinetic energy.

Can students explain the similarities and differences between a waterfall and a rollercoaster?

Curriculum Notes

This clip will be relevant for teaching Physics. This topic appears in OCR, Edexcel, AQA, WJEC KS3 and GCSE in England and Wales, CCEA GCSE in Northern Ireland and SQA National 4 and 5 and Higher in Scotland.

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