Hostname: page-component-586b7cd67f-t7czq Total loading time: 0 Render date: 2024-11-30T15:13:48.627Z Has data issue: false hasContentIssue false
  • English
  • Français

43. Notes on force, power and gravitational units

Published online by Cambridge University Press:  03 November 2016

Roger F. Wheeler
Roger F. Wheeler*
Affiliation:
Hymers College, Hull
Get access Rights & Permissions [Opens in a new window]

Abstract

An abstract is not available for this content so a preview has been provided. Please use the Get access link above for information on how to access this content.
Image of the first page of this content. For PDF version, please use the ‘Save PDF’ preceeding this image.'
Type
Class Room Notes
Information
The Mathematical Gazette , Volume 43 , Issue 346 , December 1959 , pp. 290 - 294
Copyright
Copyright © Mathematical Association 1959

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

page 292 of note 1 Some heavy dray horses belonging to a brewery were made to raise loads of 100 lb.wt. from the bottom of a deep well, by pulling horizontally on a rope passing over a pulley Watt found that they could do this at about 2½ mph. For no very precise reason, he then increased the calculated result by 50% to compensate for the losses due to friction (presumably estimating this to 1 significant figure). Finally, with a quite unwarranted optimism as to the potential accuracy of this experiment, he left 2 significant figures in his answer!

page 293 of note 3 The ingenious convention of writing Lb. (with a capital L) for lb.wt. does not commend itself for use in schools. Another notation, however, has been proposed, which is worthy of more serious consideration. This employs lbm. and lbf. for pound mass and pound force respectively, and gm. and gf. for gram mass and gram force.

page 294 of note 3 Just as they must also be excused for thinking that there is really no difference between speed and velocity after they have read about those clever particles which manage to describe circles with constant velocity, v! In this case, however, they have probably already given up trying to distinguish between these particular concepts after hearing us repeatedly talk about ‘angular velocity,’ when, (had we wished to be helpful), we should have been saying ‘angular speed;’ for, in school mathematics, where the only rotations normally considered are confined to one plane, this quantity behaves like a scalar, and so its vectorial status is better concealed until it can be properly appreciated.