Available online
Description
Two of the chief assumptions in the derivation of the pressure formula for a gas are examined.
Two of the chief assumptions in the derivation of the pressure formula for a gas are examined.
| Module code and title: | ST285, "Solids, liquids and gases" |
|---|---|
| Item code: | ST285; 03 |
| First transmission date: | 03-03-1973 |
| Published: | 1973 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:23:36 |
| + Show more... | |
| Producer: | Andrew Millington |
| Contributors: | Paul Clark; Alan Walton |
| Publisher: | BBC Open University |
| Keyword(s): | Experiments; Imperial College; Mathematical simplicity; Pressure formula for gas; Sussex University |
| Footage description: | Shots of billiard balls rebounding from the side of the billiard table. Paul Clark introduces the programme. He looks at the following assumptions of Newtonian mechanics which appear to be demonstrated by the billiard balls. 1. That the angle of reflection equals the angle of incidence. 2. That there is immediate rebound from the surface. Alan Walton explains how the validity of the first assumption can be tested. He uses a mag. board to construct a model of an apparatus which can test this assumption. Walton explains how the apparatus works. Shots of Alan Walton with the actual apparatus at Imperial College, London. He explains the components of the apparatus and how it works. Walton does the experiment and examines the results which are shown on a chart recorder. The results show how molecules are scattered on contact with a solid surface. Paul Clark with a diagram which shows the angle of reflection of a tungsten crystal. He next shows the angle of reflection for a piece of steel and compares the two. Clark shows that the angle of reflection does not equal the angle of incidence and that this holds for most common materials. Clark introduces an examination of the second assumption that there is immediate rebound from the surface in a collision. Alan Walton draws a diagram of the apparatus which can test this assumption. His commentary explains how it works. Walton performs the experiment which he has just outlined. He points out the component parts of the apparatus as he works through the experiment. Paul Clark with a model which simulates the path of a gas molecule through a tube. He explains how the molecule is impeded. Walton with the apparatus which can determine whether or not molecules stick together for any time during a collision. He explains how it works. The results of this experiment are shown on a graph. The figures are for collisions of hydrogen molecules with a nickel surface. The graph shows that molecules dwell of surfaces rather than rebound immediately. Paul Clark examines two new assumptions which were formulated as a result of the experiments. 1. Angle of reflection is not equal to angle of incidence. 2. Delayed rebound from a surface. Clark explains the importance of these new assumptions. Alan Walton demonstrates an experiment in which momentum is transferred from a rotating disc to a stationary one separated by a few mm. of air. Paul Clark, with diagrams, explains how this transfer of momentum takes place. He then predicts that an increase in temperature will result in an increased momentum transfer. Alan Walton performs an experiment to test this prediction. He explains the apparatus involved and then does the experiment. Paul Clark sums up. |
| Master spool number: | 6HT/70792 |
| Production number: | 00525_1027 |
| Videofinder number: | 680 |
| Available to public: | no |
