       Yard Rule Support for Students Preferring to Use the Imperial System  Home | The EC Decision | What I Stand For | Don't Give Them a Centimetre | What's Happened to my 4 Pint of Milk? | Units in Transport | Compulsory Metric in Schools | Support for Students Preferring to Use the Imperial System | About Me | Favorite Links A guide to using imperial in school subjects

The first step in being able to use imperial is to have the conversion factors from metric to imperial to hand, so questions can be converted into the appropriate units. Please note the below conversion rates are rounded to a degree sufficiant for most purposes, for the precise conversion rates go to www.google.com and type in the desired conversion, such as '1 Joule in BTU'. This will work in most cases.  Millimetres - inches /25.4 metres - feet x3.281 Kilometres - miles x0.621 Litres - pints x1.76 Millilitres - fluid ounces (UK) x0.035 Kelvin - rankine /9 5ths Celsius - Fahrenheit /9 5ths, +32 (roughly double and add 30 for 20-100F) Kilogram - pound x2.205 Gram - slug x0.000,068522 Newton - pound force x0.225 Newton - poundal x 7.2330 Joule - BTU x0.00094782 Joule - foot-pound-force x0.737562149277 Joule - foot-poundal x23.7  It is also helpful to know how to convert between imperial units. Although the numbers are not multiples of ten, this is no harder to do than it is in metric (presuming in some cases you do have a calculator to hand, if you don't your computer will have). To convert in the opposite direction to the conversions shown below (e.g. from feet to miles), just do the inverse of what is shown.

 miles - feet x5,280, or x80, then x66 miles - yards x1,760, or x80 then x22 feet - inches x12 yards - feet x3 tons - pounds x2,240 ounces - pounds /16 fluid ounces - pints /20 gallons - pints x8 stones - pounds x14 Feet/second - MPH /5280, then x60 twice

A note for chemists: One fluid ounce (fl oz) of water at 62°F (521.67°R) weighs one ounce (oz) exactly.

Also, 1 gallon (gal) of water at 62°F (521.67°R) weighs 10 pounds (lb) exactly.

THE FPS SYSTEM

A slight variant on imperial which is better adapted to science and maths is the FPS system. This stands for Foot-Pound-Second, and the system has been around for some considerable time. The system was designed to fit the essential science equation F=MA, or force equals mass times acceleration. It does this by replacing the force unit PoundForce (lbf) with the Poundal (pdl). One poundal is the force required to accelerate an object with one pound (lb) of mass at 1 foot per second per second (ft/s²).

The FPS equivalent to the Kelvin scale is the Rankine scale (°R). This uses the same degree as Fahrenheit, but starts from absolute zero (-459.67°F).

Note: Alternatively, you can replace the weight unit, pound (lb) with a unit called the slug (sl). This is a matter of personal choice, but in my opinion it is better to use the poundal for the sake of uniformity, as it is a little more frequently used, and is better for physics as it is not limited to use on Earth's surface. Also, using the poundal does not upset the fl oz - oz relationship (see above 'note for chemists').

ENERGY

The imperial unit of energy is the BTU, or British Thermal Unit, which is the energy required to raise the temperature of a pound of water by one degree Fahrenheit. This is essentially the same function as the calorie serves in metric. In FPS, you can also use the foot-pound-force or the foot-poundal, depending on whether you use the slug or poundal respectively. These units are coherent, and fit physics equations.

A FEW PHYSICAL VALUES

Speed of sound: 1128 ft/s

Speed of light: 753,912,264 ft/s

Acceleration due to gravity: 32.15 ft/s²

Atmospheric pressure (ground level, Earth): 68087.256 pdl/ft²

Earth-Sun distance (1 Astronomical Unit): Approx. 93 million miles.  Don't use imperial merely out of defiance. Use it because it is better. Teach imperial, use imperial, save imperial