Metric yardstick
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This article gives some rough rules of thumb for comprehending the metric system in terms of everyday life.
Contents |
[edit] Metric yardsticks based on everyday objects
[edit] Length
- One meter equals roughly one (longish) step of a tall adult man. Two cubits as perceived by such a person may come to about one meter.
- The length of a TWO-second pendulum is approximately one meter.
- One kilometer equals ten minutes' walk.
- The distance between nails of fingers pressed together is roughly 1 cm or 10 mm.
- the width of a fingernail is roughly 1 cm.
- The cubit arm (forearm from elbow to fingertips) is roughly 50 cm. This is known as metric cubit and has been used in some countries.
- The width of man's hand is about one decimeter or 10 cm. That is almost the same as the old English unit "hand".
- The side of a matchbox is 5 cm.
[edit] Area
- A large soccer field has an area of one hectare (10,000 square meters).
- The area covered by a large umbrella is roughly one square meter.
[edit] Volume
- A cube of one hand (1 decimeter) per side is equal to one liter.
- A drop of water (or water-based solution, like milk, tears, etc.) is very close to 0.05 milliliters. 20 drops make one milliliter. This is an approximation used in chemical engineering.[citation needed] One liter is therefore roughly 20,000 drops.
- Both the British and American pints are close to 1/2 L, sometimes called the "metric pint".
- Soft drinks are sold in 1, 1.5, 2 and 3 liter bottles.
Cooks beware - Cup sizes differ widely.
| Nation | Standard cooking cup |
|---|---|
| Japan | 180 ml |
| USA | 237 ml? |
| Australia | 250 ml |
[edit] Mass
- One milliliter (1 ml) of water is one gram (1 g), and therefore 1000 milliliters of water (1 l) is 1 kilogram (kg).
- One liter (1 l) of water is one kilogram (1 kg), and therefore 1000 liters of water (a cubic meter - 1 m3) is 1 tonne.
- One tonne (1 t = 1000 kg) is roughly the mass of an economy motor car.
- One U.S. "nickel" (5 cent coin) has a mass of 5 g.
- One litre of a soft drink has a mass of roughly 1 kg.
[edit] Force
- A small apple on Earth exerts a force due to gravity of about one newton (N). (Remember Newton's apple)
- One kilogram at the Earth's surface exerts a force due to gravity very close to 10 N.
- One newton-meter torque is roughly the increase in torque by adding a small apple to the end of an outstretched walking stick.
[edit] Temperature
- For Celsius temperatures
- 30 is hot
- 20 is nice
- 10 is chilly
- 0 is ice.
- Normal room temperature is roughly 22 °C
- An outside temperature of 300 kelvins (273 + 27 °C) means bikini weather.
- The USMA (United States Metrication Association) promotes the following jingle to spread awareness of Celsius: "0 is cold, 10 is not, 20 is warm, and 30 is hot"
[edit] Pressure
- Normal air pressure at sea-level is around 100 kilopascals. It equals approximately 1 kgf/cm2
- Every ten metres' depth of seawater exerts about one bar or 100 kPa or 1 kg/cm2 of additional pressure.
[edit] Conversion hints
For users of the English system there are a few simple equivalents and conversion factors that help in learning to be comfortable with the metric system:
[edit] Near equivalents
The following units are the same within a few percent. The slightly larger unit is listed first
[edit] Approximate conversion factors
[edit] Length
- 1 nautical mile = 1852 m
- 1 mile ≈ 1.6 km
- 1 meter ≈ 1.1 yard ≈ 3.28 ft
- 1 yard ≈ 0.9 meters
- 1 foot = 0.3048 m, very roughly 1/3 of a meter; 10 ft = 3.048 m
- 1 inch ≈ 25 mm, 4 inches ≈ 10 cm
Note- 1cm ≈ 3/8in.
[edit] Surface
[edit] Mass
[edit] Volume
- 1 US cup ≈ 240 ml
- 1 teaspoon = 5 ml
[edit] Celsius landmarks
The table below lists easy to remember or particularly important Celsius temperatures.
| °C | °F | Landmark |
|---|---|---|
| -273 | –459.67 | Absolute zero (zero kelvins). |
| -40 | -40 | Numeric conversion exact. |
| -11.4 | +11.4 | |
| 0 | 32 | Freezing point of pure water. Numeric conversion exact. |
| 4 | 40 | Point of maximum density of water in liquid form. Also temperature of domestic refrigerators. |
| 10 | 50 | Numeric conversion exact. |
| 16 | 61 | Numeric conversion exact. |
| 22 | 72 | Room temperature |
| 28 | 82 | Numeric conversion exact. |
| 30 | 86 | Beach weather. Numeric conversion exact. |
| 37 | 98.6 | Human Body temperature. Numeric conversion exact |
| 37.5 | 100 | The ton. Old mark for a hot day in Australia. Uncomfortable. |
| 40 | 104 | Hot tub. Numeric conversion exact. Feverish baby - time to get help. |
| 100 | 212 | Numeric conversion exact. Boiling point of pure water. |
