The SI system of units is a wonderfully logical and functional system of units of measurement. In the SI system all units can be expressed in terms of a few fundamental, independently defined base units such as the second, the metre and the kilogram. (I freely admit that the fact the kilogram as a base unit is one of the less logical parts of the system.) When working in the base-10 SI system, no conversion factors are required and everything fits together beautifully.
The other day I realised we are routinely using at least one unit which is more complex than it need be. It is that of vehicle fuel consumption, typically expressed in SI countries in litres per 100 kilometres. (It’s interesting to note that in countries that use Imperial units, the custom is to use the reciprocal unit, that is, miles per gallon.)
So, what would be a better unit? Let’s simplify! Volume (in litres) divided by distance (in kilometres) is area.
The beauty of this unit is that it does not feature the distance driven anywhere. It is superfluous because the distance driven is directly proportional to the fuel consumption. A neat way to visualise this is to imagine that when you drive, your car leaves behind it cylinder (or cuboid) of fuel with its cross-sectional area as above and its length the distance you’ve travelled.
So when you’re buying your next car, make sure it consumes less than 50 thousand square micrometers of fuel.
Wht is the SI unit for car fuel consuption?
The SI system of units is a wonderfully logical and functional system of units of measurement. In the SI system all units can be expressed in terms of a few fundamental, independently defined base units such as the second, the metre and the kilogram. (I freely admit that the fact the kilogram as a base unit is one of the less logical parts of the system.) When working in the base-10 SI system, no conversion factors are required and everything fits together beautifully.
The other day I realised we are routinely using at least one unit which is more complex than it need be. It is that of vehicle fuel consumption, typically expressed in SI countries in litres per 100 kilometres. (It’s interesting to note that in countries that use Imperial units, the custom is to use the reciprocal unit, that is, miles per gallon.)
So, what would be a better unit? Let’s simplify! Volume (in litres) divided by distance (in kilometres) is area.
1l/100km = 1dm3/100km = 1*10-3m3/105m = 1*10-8m2 = 10000μm2.
The beauty of this unit is that it does not feature the distance driven anywhere. It is superfluous because the distance driven is directly proportional to the fuel consumption. A neat way to visualise this is to imagine that when you drive, your car leaves behind it cylinder (or cuboid) of fuel with its cross-sectional area as above and its length the distance you’ve travelled.
So when you’re buying your next car, make sure it consumes less than 50 thousand square micrometers of fuel.