Archive for the ‘Science’ Category

Cross-section of Fuel

Monday, 27 April 2009

Here’s another, brief, post on the subject of dimensional analysis; it concerns a curious interpretation of dimensions. [Previous posts concerned statistics and kinematics.]

Consider cars. A typical fuel efficiency is
≈ 40 mpg (miles / gallon [UK])
≈ 14 km / litre = 14 m / cc = 14 mm / mm3

Expressed differently (taking the reciprocal), this is about
≈ 4 fl oz [UK] / mi
≈ 70 ml / km = 70 cc / km = 70 mm3 / m
≈ 70,000 μ2 = 70,000 μm2 = 0.07 mm2

What’s that? It’s a unit of area.

If you imagine forming a tube of fuel as the car uses it (as the car goes along), then that’s the tube’s cross-sectional area.


Colour Mixing

Sunday, 26 April 2009

There seems to be some confusion about what the primary and secondary colours are. Well, it depends.


Dimensional Analysis of the Kinematic Equations

Sunday, 26 April 2009

To help to remember the kinematic equations, it may be useful to know a little dimensional analysis.


Planetary Mnemonic

Tuesday, 21 April 2009

Here’s something I noticed that might help people to remember the order of some of the planets – mainly the gas giants.

Beyond Mars are:

  • Jupiter
  • Saturn
  • Uranus
  • Neptune

notice the initial letters in the order SUN away from the Sun.

The Kinematic Equations

Saturday, 4 April 2009

It seems that the kinematic equations can all be derived from some simple definitions.