Available online
Description
Two rival models which seek to explain viscosity in liquids are presented and evaluated.
Two rival models which seek to explain viscosity in liquids are presented and evaluated.
| Module code and title: | ST285, "Solids, liquids and gases" |
|---|---|
| Item code: | ST285; 10 |
| First transmission date: | 16-06-1973 |
| Published: | 1973 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:20 |
| + Show more... | |
| Producer: | Andrew Millington |
| Contributors: | David Betts; Paul Clark; Alan Walton |
| Publisher: | BBC Open University |
| Keyword(s): | Atomic model; Compressed gas; Loosened solid; Model building; Molecular weight; Non-drip paint; Pressure; Temperature |
| Footage description: | David Betts introduces the programme. He explains the programme's format, a presentation of rival models which explain viscosity in liquids with himself as an independent adjudicator. He then gives a brief definition of viscosity. The viscosity formula is captioned. Alan Walton presents his model for a viscous liquid - the dense gas model. He uses a FVT surface and animated diagrams of a gas contained between a moving and a stationary plate as visual aids. David Betts briefly introduces Paul Clark. Paul Clark presents his model for a viscous liquid - a cell model with wanderers. He uses a molecular model of a solid, a graphics board and diagrams of potential energy wells as visual aids. Alan Walton tests his model with a prediction of an increase in viscosity as temperature rises. He uses a graphics board as a visual aid. Paul Clark tests his model with a prediction of a decrease in viscosity as temperature rises. He uses a graphics board and diagrams as visual aids. The predictive powers of both models are put to the test. Film shots of cold and hot treacle being poured from containers. The hot treacle is obviously less viscous. Betts evaluates the models on the basis of this experiment. Paul Clark next uses his model to make a prevarication of viscosity with pressure. Using a graphics board and diagrams, he predicts that a rise in pressure will increase viscosity. Alan Walton uses his model to predict that viscosity is independent of pressure. Animated diagrams are used as visual aids. Betts criticises Walton's model on this point and Walton modifies the model to bring it into line with experimental results. He uses animated molecular models and graphics boards as visual aids. Betts evaluates the models as presented so far and goes on to present them with a third challenge - Can they explain variation of viscosity with variation of molecular weight. Shots of an experiment in which liquids of different molecular weights flow from tubes. The flow variations are plotted on a graph. Paul Clark uses his model to explain why viscosity decreases as molecular weight decreases. He uses a graphics board as visual aid. Alan Walton does the same for his model. He predicts the same result. A graphics board is used as visual aid. Betts evaluates the models on the data presented so far. Next Betts, dipping a brush into a tin of thixotropic paint, challenges the models to explain this phenomenon. Paul Clark uses his model to explain the phenomenon. He uses a graphics board as visual aid. Alan Walton explains the phenomenon in terms of his model. He uses a graphics board as visual aid. Betts sums up. |
| Master spool number: | 6HT/71023 |
| Production number: | 00525_1149 |
| Videofinder number: | 687 |
| Available to public: | no |
