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In physics, we usually need to convert units from one standard to another, such as mile to meter, hour to second, meter to an inch, feet to meter, kilogram to the gram, and so on. You’ll need to know how to convert meter to the inch, a kilometer to a mile, and so on, such as 1m = 39.37in or 1km = 0.6214mi.
When the quantity expressed is not in our familiar format, such as when we want to convert units to SI units, unit conversions are required (in physics, we always convert units to SI units). We may not be familiar with the value of a physical quantity when expressed in a different unit format. Instead, you might want to add the values in a calculation that involves another unit. In this article, we have provided different conversion units for measuring different parameters. Let us start by understanding the conversion of units in the coming section.
Conversion of Units
The primary focus of this chapter is to tackle the conversion of units of measurement of various quantities. However, before we start, it is essential to understand fundamental and derived physical quantities and their units.
To learn how to convert units of physical quantities, it is necessary to be aware of the terms–dimensional formula and dimension equation. First, check these details about fundamental and derived quantities.
Fundamental Quantities and Derived Quantities
All measurable physical quantities can be primarily classified into two types, which are –
A small group of physical quantities are considered as fundamental quantities or primary quantities which are used to derive other physical quantities.
For Example: Mass, time, length, electric current, the luminous intensity of light, temperature, amount of substance are all fundamental quantities.
Also referred to as secondary quantities, derived quantities are formed from primary or fundamental quantities.
For Example: By dividing distance by time, we can calculate the speed of an object. Hence, speed is a prime example of a derived quantity.
Additionally, if we multiply the breadth, length and height of an object, we get to derive the volume. So volume is also another example of a derived quantity.
Fundamental and Derived Units
Units selected for primary physical quantities are known as fundamental units. Meanwhile, those units which are formed with the help of fundamental units are termed derived units.
For Example: Speed is a derived quantity whose unit is determined as distance/time, i.e. metre/second. Here, you can notice that metre and second are fundamental units while the unit of speed, i.e, metre/second, is a derived unit.
A Complete Unit Conversion Table
To solve numerical problems in the case of unit conversion questions in physics, consulting a tabulated form of unit conversions is highly important, especially for beginners.
Several tables containing the unit conversion formulas are given below, which sum up almost every essential physical quantity. Each table contains various units and their conversions of a specific physical quantity, fundamental or derived. Let us now learn unit conversion with the help of the unit conversion table.
Basic Unit Conversion Table – Length
|
Sl. No. |
Different Types of Measurement |
In Terms of Metre |
|
1. |
1 mm |
1 x 10-3 m |
|
2. |
1 km |
1 x 103 m |
|
3. |
1 inch |
2.54 x 10-2 m |
|
4. |
1 foot |
3048 x 10-4 m |
|
5. |
1 light year |
946 x 1013 m |
|
6. |
1 mile |
16 x 102 m |
|
7. |
1 angstrom |
1 x 10-10 m |
Unit Conversion List – Mass
|
Sl. No. |
Different Types of Measurement |
In Terms of Gram |
|
1. |
1 mg |
1 x 10-3 g |
|
2. |
1 kg |
1 x 103 g |
|
3. |
1 stone |
6.35 x 102 g |
|
4. |
1 pound |
4.53 x 102 g |
|
5. |
1 ounce |
0.283 x 102 g |
Units of Measurement Conversion Table – Volume
|
Sl. No. |
Different Types of Measurement |
In Terms of Litre |
|
1. |
1 ml |
1 x 10-3 l |
|
2. |
1 kl |
1 x 103 l |
|
3. |
1 cubic inch |
1639 x 10-5 l |
|
4. |
1 cubic foot |
0.283 x 102 l |
|
5. |
1 gallon |
0.03785 x 102 l |
Units and Conversions – Time
|
Sl. No. |
Different Types of Measurement |
In Terms of Seconds |
|
1. |
1 min |
60 s |
|
2. |
1 hour |
3600 s |
|
3. |
1 day |
86400 s |
|
4. |
1 week |
604800 s< /p> |
|
5. |
1 month |
2592000 s |
|
6. |
1 year |
31104000 s |
Unit Conversion Table – Energy
|
Sl. No. |
Different Types of Measurement |
In Terms of Joule |
|
1. |
1 kw-hr |
3.6 x 106 J |
|
2. |
1 erg |
1 x 10-7 J |
|
3. |
1 BTU |
1.055 x 103 J |
|
4. |
1 calorie |
4186 x 10-3 J |
|
5. |
1 electron volt |
1.602 x 10-19 J |
Unit Conversion Table- Power
|
SI. No. |
Different Types of Measurement |
In Terms of Watt |
|
|
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 |
Numerical Problems from Unit Conversion Tables
Numerical problems with the conversion of units in physics are quite common in exams. For example, the following question is frequently asked –
1. State the Relationship Between Dyne and Newton?
Ans: As we know, dyne and Newton are units of force. The dimensional formula of force is [MLT-2].
Hence, 1 Newton = 1 x kg x m x s-2 = 1 x 103 g x 103cm x s-2 = 1 x 106 g x cm x s-2
So, Newton = 106 dyne.
At , we hope that this discussion on the Conversion of Units will help you attain high marks in the upcoming physics exams. Moreover, make sure to download our app to access study materials and online classes easily.