Monday, 18 August 2008

New activity - See how they run!

Why do some lavas flow further and more quickly than others? Find out by trying our latest Earthlearningidea 'See how they run'.
Ask your pupils why they think that some volcanoes erupt lava that can flow for many kilometres, whilst others tend to produce lava domes with no runny lava at all. Pupils can then investigate some of the factors that control the viscosity (or 'stickiness') of fluids, using a viscous fluid like treacle as a substitute for lava.

At the end of this activity your pupils should be able to explain that the viscosity of a fluid depends on several variables including temperature, content of solid particles and gas content. They will know that a fluid with low viscosity will flow further than one of high viscosity. They will appreciate that lavas may contain liquids, solids and gases and that volcanoes emitting lava of high viscosity may be more dangerous than ones with low viscosity lava, which flows away more freely.

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