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Do you know what units are?
Well, Units are those physical quantities which are used for measuring anything or we can say it tells us about the amount of any substance. Like, Metre is the unit for measuring length, kilogram measures weight, cubic metre tells us the amount of volume.
We have different units, and can convert them into each other.
You will be provided with tables which help you in conversion, before proceeding, it is necessary to know different systems of units.
System of Units
In the system of units, some quantities are fundamental, while others can be derived from them. Mostly, “Length, Mass and time” are considered as fundamental quantities while others can be derived from them.
Commonly, Four system of units are used as following:-
- MKS : M – metre, K – Kilogram, S – Second
metre is for measuring length, K is for kilogram and S is for measuring Time.
- CGS : C – Centimetre, G – Gram, S – Second
Centimetre is for measuring length, G is for measuring Weight and S – Second is the unit of time.
- FPS – F – Feet (Unit of length), P – Pound ( Unit Of Weight) and S – Second (Unit of Time).
- SI Unit – SI is the international system of units, This system has 7 fundamental quantities and others can be derived from them.
|
S. No. |
Name of the Quantity |
SI Unit |
SI Unit Symbol |
|
1. |
Length (l) |
metre |
m |
|
2. |
Mass (M) |
Kilogram |
kg |
|
3. |
Time (T) |
Second |
s |
|
4. |
Electric current (I) |
Ampere |
A |
|
5. |
Thermodynamic temperature (Θ) |
Kelvin |
K |
|
6. |
Amount of substance (N) |
Mole |
mol |
|
7. |
Luminous intensity (J) |
Candela |
cd |
So, these are the four common systems of units, and now we are going to discuss their conversion, by using a conversion table.
Length Unit Conversion
|
1 millimetre |
10-3 metre |
|
1 centimetre |
10-2 metre |
|
1 decimetre |
10-1 metre |
|
1 decametre |
10 metres |
|
1 hectometre |
102 metres |
|
1 kilometre |
103 metres |
|
1 inch |
2.54 × 10-2 metres |
|
1 foot |
0.3048 metres |
|
1 Angstrom |
10-10 metres |
|
1 Fermi |
10-15 metres |
|
1 light year |
0.946 × 1016 metres |
|
1 mile |
1.609344 km |
Volume Unit Conversion
|
1 millilitre |
10-3 litre |
|
1 centilitre |
10-2 litre |
|
1 decilitre |
10-1 litre |
|
1 decalitre |
10 litres |
|
1 hectolitre |
102 litres |
|
1 kilolitre |
103 litres |
|
1 cubic inch |
1.639 × 10-2 litres |
|
1 gallon |
3.785 litres |
|
1 cubic foot |
28.316 litres |
Mass Conversion
|
1 milligram |
10-3 gram |
|
1 centigram |
10-2 gram |
|
1 decigram |
10-1 gram |
|
1 decagram |
10 gram |
|
1 hectogram |
102 gram |
|
1 kilogram |
103 grams |
|
1 stone |
6350.29 grams |
|
1 pound |
453.592 grams |
|
1 ounce |
28.3495 grams |
Time Unit Conversion
|
1 minute |
60 seconds |
|
1 hour |
60 minutes / 3600 seconds |
|
1 day |
24 hours |
|
1 week |
7 days |
|
1 year |
365 days |
Area Unit Conversion
|
1 sq. inch |
6.4516 x 10-4 square metre |
|
1 sq. foot |
9.2903 x 10-2 square metre |
|
1 acre |
4.0468 x 103 square metre |
|
1 hectare |
1 x 104 square metre |
|
1 sq. mile |
2.5888 x 106 square metre |
|
1 barn |
1 x 10-28 square metre |
Force Unit Conversion
|
1 dyne |
1 x 10-5 Newton |
|
1 pound |
4.448 Newton |
Power Unit Conversion
|
1 erg/sec |
1 x 10-5 watt |
|
1 BTU/hr |
0.2930 watt |
|
1 foot-pound/ sec |
1.356 watt |
|
1 horsepower |
745.7 watt |
|
1 calorie/sec |
4.186 watt |
Energy Unit Conversion
|
1 BTU (British thermal unit) |
1055 Joule |
|
1 erg |
1×10-7 Joule |
|
1 foot-pound |
1.356 Joule |
|
1 calorie |
4.186 Joule |
|
1 kilowatt-hour |
3.6×106 Joule |
|
1 electron volt |
1.602×10-19 Joule |
|
1 litre atmosphere |
101.13 Joule |
So, these are the tables which will help us in converting them into each other. Some examples are given below, which will make your understanding clear and better.
Examples
1. A box weighs 5 pounds, convert this weight into kilograms.
Ans: m = 5 pounds
We know that,
1 pound = 453.592 grams
⇒5 pound=5× 453.592 grams
=2267.96 grams
As we know,
1000 grams = 1 kilogram
⇒1 gram=10-3 kilogram
2267.96 grams = 10-3 × 2267.96 kilogram
= 2.267 kilograms
2. Distance between two cities is 6000 cm, calculate it in kilometres.
Ans: 1 km = 1000 m
1 m = 100 cm
1 cm = 10-2 m
6000 cm = 6000 × 10-2 m
= 60 m
60 m = 60 × 10-3 km
= 0.06 km
Conclusion
We have studied unit conversion. As it is a very important part of our daily life. It is important also, as Different countries have different units for measuring physical quantities. So it becomes difficult to understand this for us. That’s why we should have knowledge of unit conversion.
