Monday, 29 November 2010

Going Metric.

When studying Mechanical Engineering at college, the lecturer drummed  into us the importance of  the units of measurement. All of our calculations had to show not only the numbers but all of the units and the answer with the correctly derived unit. The beauty of the S.I. system of units is that it can be calculated like this, even if you didn't know the correct unit for Work, the fact it is calculated by Force (N) * Distance moved (m) would tell you the correct unit is the Nm. or the Joule to give it another name.

I therefore get slightly annoyed at the British press (for whom all scientists, engineers or anyone who can wire a plug is called a 'Boffin') for constantly using the non SI and non Imperial unit of measurement called 'The double decker bus'. Thus a story about a submarine captain losing his command is dumbed down because the multi million pound, nuclear powered, killing machine (sorry, 'deterrent') that he grounded, weighs 7800 tonnes - "equivalent to nearly 1,000 double-decker buses".

Fractions are best avoided in practice
Fortunately, there is a handy calculator available that will allow you to convert lengths, areas, heights and speeds into manageable 'DDB' units: DDB Calculator. Thus, I know that 1 Blue Whale is equivalent to 3.58 double decker buses and 1 Statue of Liberty is equivalent to 10.6 double decker buses. I will endeavour to use DDB units with my customers when discussing their wells and the performance of our drill bits. I'm sure they'll be more impressed that a bit can drill at 0.1219 double decker buses/hour instead of 30 feet/hour.

1 comment:

  1. Funnily enough Ben has a chemistry test today and all weekend has ben muttereing about pressure and density and solutions & one of his questions to Si was answered along the lines of your lecturer - about knowing your units that is, not about DDB's - don't think we have them here in the land of the BB (bendy bus)