| Measure of distance |
|
| 12 inches = 1 foot |
|
| 3 feet = 1 yard |
|
| 1760 yards = 1 mile |
5,280 feet |
| 1 inch = 2.54 cm |
|
| 1 metre = 1.09 yards |
|
| 1 metre = 39.4 inches |
|
| 1 furlong = 220 yards |
|
| 1 fathom = 6 feet |
|
| 1 sea mile = 6080 feet |
1 knot = 1 sea mile per second |
| 1 Km = 0.621 miles |
conversion factor about 5 / 8 |
| Measure of area |
|
| 484 sq yds = 1 chain |
|
| 10 chains = 1 acre |
4840 sq yds; possibly the area of land an ox
could plough in one day |
| 1 hectare = 10,000 sq metres |
a metric measurement of area |
| 1 hectare = 2.47 acres |
|
| 640 acres = 1 sq mile |
|
| 100 hectares = 1 sq Km |
|
| Measure of volume |
|
| 1 litre = 1,000 cc |
cubic centimetres |
| 1 litre = 100 cl |
centilitres; wine bottles hold 70 cl (about six glasses) |
| 1 litre water weighs 1 Kg |
|
| 1 litre = 0.22 gallons |
1.76 pints; to convert litres to gallons divide by 5
and add ten percent |
| 1 litre = 1.76 pints |
|
| 1 gallon = 277 cubic inches |
1 gallon is defined as the volume of 10 lbs of water |
| 1 cu ft = 6.24 gallons |
|
| 1 dram = 1/8 fl oz |
|
| 1 teaspoon |
About 5 ml. Teaspoon's vary in size so always
use a calibrated measuring spoon (eg from the chemist) for
medicines, and cooking. |
| 1 pint |
the volume of 20 fluid ounces of water; about 568 ml |
| 2 pints = 1 quart |
|
| 8 pints = 1 gallon |
|
| 500 ml = 0.88 pint |
500 ml is about ten percent short of one pint |
| Measure of weight |
Avoirdupois |
| 16 oz = 1 lb |
lb is shorthand for pound; oz = ounce |
| 14 lb = 1 stone |
|
| 112 lb = 1 cwt |
the weight of a sack of grain |
| 20 cwt = 1 ton |
2240 lb |
| 1,000 grams = 1 Kg |
|
| 1,000 Kg = 1 metric tonne |
|
| 1 kg = 2.2 lb |
|
| 1 lb = 454 grams |
|
| 1 tonne = 0.984 ton |
one metric tonne is close to one imperial ton |
| 1 lb = 7000 grains |
the grain was originally the weight of a barley seed |
| 1 oz troy = 480 grains |
obsolete |
| Constants |
|
| Speed of light in vacuum |
3 X 10E8 metres per second; (10E8 = 100 million) |
| Speed of sound in air |
1,100 feet per second or about 750 mph or 340 metres
per second |
| Radial distance of lightning |
Divide time between flash and bang in seconds by five
to give distance in miles |
| pi |
3.1416 or as a fraction about 22 / 7 |
| 1 radian |
57 degrees approx; (360 deg = 2pi radians) |
| Base (e) used in natural logs |
2.7183 |
| Mean radius of earth |
6,371 Km about |
| Distance to the moon |
384,400 Km about (centre to centre); one way delay
about one second |
| Distance to the sun |
150 million Km about; 500 seconds at the speed of light |
| Geosynchronous orbit |
35,786 Km; two way delay about 0.25 second |
| Distance to planet Mars |
70 million Km approx; two way delay about ten
minutes |
| 1 Atmosphere (Bar) |
760 mm column of mercury or a pressure of about 1 Kg
per sq cm (about 15 psi) |
| 60 mph = 88 feet per second |
|
| 1 knot = 1.7 fps about |
|
| 50 knots = 58 mph about |
|
| Acceleration due to gravity |
32.2 feet per second per second or 981 cm per sec per
sec |
| Specific gravity |
|
| Water |
1 |
| Brass |
8.5 about |
| Copper |
8 |
| Glass |
2.5 about |
| Gold |
19.3 |
| Iron (wrought) |
7.9 |
| Lead |
11.4 |
| Mercury |
13.6 |
| Platinum |
21.5 |
| Silver |
10.5 |
| Alcohol |
0.8 |
| Methylated spirit |
0.83 |
| Petrol |
0.7 |
| Ice |
0.917 |
| Work and heat |
|
| 1 Watt = 1 Joule per sec |
10E7 ergs per sec |
| 1 Horse Power (HP) |
550 ft lbs per sec or about 746 watts |
| 1 Kw |
102 Kg metres per sec |
| Coefficient of expansion |
|
| Brass |
1.9 X 10E-5 |
| Copper |
1.67 X 10E-5 |
| Iron |
1.1 X 10E-5 about; extremes of temperature can
cause railway
track to buckle or fracture, so track must be designed to allow
for this and be monitored. |
| Radio |
|
| Boltzmann's constant (k) |
1.38 X 10E-23 Joules per deg K or equivalent radio
noise power (kTB) minus 228.6 dbW per deg K per Hz bandwidth. |
| Spare |
|
Disclaimer: this information is provided as a guide for retired people. All numbers are approximate and no liability is accepted for errors.
|
