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KILSBY AUSTRALIA | transport policy, planning and management advice |
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Units of Measurement Old joke. We know that power is the rate of work, ie work divided by time. We know that knowledge is power. We know that time is money. Therefore (juggle juggle) money is work divided by knowledge. From which it follows that, for a given amount of work, the more you know, the less you are likely to earn: or, equivalently, the more you pay someone the less likely they are to know anything. Or, for a given amount of money, the more you know the harder you work. Boom boom. One thing this does do, however, is emphasise the importance of using measurement units appropriately. Power is not the same thing as energy. And, as a headline writer in the Sydney Morning Herald failed to realise recently, acceleration is not velocity.  Gravitational pull = 32 feet per second per second Terminal velocity of skydiver = speed at which downward pull of gravity equals upward force of air resistance = approximately 120 feet per second. It can matter. Space probes have been lost because engineers had failed to distinguish between metric and imperial measurements. In 1883 natives lost a substantial slice of south-west Africa (part of today's Namibia) to the German Empire because a treaty specifying land transfer in miles failed to say whether this was, as the locals thought, English land miles or, as the well-armed Germans later insisted, German geographical miles. With each geographical mile being the equivalent of four nautical miles, this "mattered". There is a comprehensive review of units of measurement elsewhere on the web. It opens with a sage quote: Units resemble sports officials: the only time you really pay attention to them is when something stupid happens." These thoughts were prompted by looking at data in the Sydney Ports Annual Report for 2001. Container throughput is a useful measure of port activity but it does not reflect the value of containerised port trade to its state or city - it depends on what is in them and which way they are going. Containerised exports through Sydney could increase by over 50% without changing the number of containers going through the port. Summarising the second Table on page 20:
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