Units of Measurement

Unit Conversions and measurements calculations are fundamental requirements to solve any

problem of Physics. What would happen if there were no units? Can you imagine? Physics will

get converted into Mathematics by becoming the study of all physical quantities only by

numbers and nothing else. People in the past used to measure they walked by counting the

number of steps it took them to travel or complete that distance. So, it is obvious that the

measurement was never accurate, and every quantities in physics were measured only by

numbers. Hence, it was the need of that time to introduce some kind of identity that could make

measurements are more accurate and easily understandable. In this article, you’ll understand what SI units are, what are different types of units, and how they are converted for the reason of measurement.

What Are Units?

Units are basic standards that are essential if we want to express or compare any physical

quantity in physical terms. A physical quantity is a largely used term, especially in the field of

science. Physical Quantities in science are of two types: Derived Quantities & Underived

Quantities(Fundamental Quantities).

To understand how units and physical quantities are linked to each other and work cordially

together let’s take one scenario where there is one race, the length of the race track is the

physical quantity, and how we measure this physical quantity i.e. length is called a unit. So, as

we know already, we measure the distance or length of any track in meters or kilometers

generally.

But, here comes a problem, not every unit like meter, inches, or miles can be made an

international standards unit that could be used everywhere. A good unit is that which is easily

available, independent of any external physical factors like space, and universally accepted.

What Is Unit Conversion and Why It Is Needed?

The term “unit conversion” is very much related to conversion or transformation happening when one physical quantity is going for its measurement from one system of units to some other unit systems. 

To understand what is the actual need for conversion of any unit from one to another, let’s take one example. Suppose, there is a copper wire, and there is some amount of electricity flowing inside it. So, the current that is flowing inside the copper wire is the physical quantity. How we will measure this current is what the unit brings to the solution. We know that the current SI unit is Charge divided per unit time. We don’t have the fundamental unit for current directly but we can produce its unit by the formula. The current SI units come to be Ampere. One Ampere is equal to 1 Coulomb of charge transfer that took place in 1 second from the copper wire. 

The conversion is needed if there is a large amount of electricity flowing from a thick wire. In that case, the amount of current flowing will not be as 1 Ampere or 5 Ampere. It will range from 1000 Ampere to even 1000000 Amperes. It is very complicated to use this measurement in calculations. Hence, there is a need for the conversion of units. 

Conversion Factors

A conversion factor is a mathematical identity that is used in the conversion of units from one to another, such as liter to kiloliter. A conversion factor is a number that can be multiplied or divided into one unit for the measurement to convert it into the other unit. 

Example 1 – Jackson wants to find out how many seconds are in 2 hours and 30 minutes. 

Answer. We shall think that hours and minutes are two separate units that are used to represent time and they are used together. So this is the beauty of units and units conversion.

Step 1. Identify the final unit that is asked in the question. Here, it is in seconds. 

Step 2. Convert the biggest unit of that quantity into a level next lower to it. This means that if the time is given in hours, then think of another unit that denotes time and is lower than the original unit, here we know that minutes are lower than hours.

Step 3. Now, convert the hours time into the minutes time.

2 hours  = 2 x 1 hour = 2 x 60 minutes = 120 minutes. 

Step 4. See any other number written with the same units, if there is combine both the numbers and convert them together. Here, 120 minutes and 30 minutes are in the same units. So, adding up both the numbers, we get 150 minutes.

Step5. Convert the added product into the final unit either by multiplication or division.

Here, 150 minutes can be converted into seconds by multiplying 60, because in one minute you have 60 seconds.

150 minutes = 150 x 1 minute = 150 x 60 seconds = 9000 seconds.

Hence, Jackson got the answer.

There are 9000 seconds in 2 hours and 30 minutes.

This is how you use units and conversion factors to get the desired answer in the desired unit.

Conclusion

Conversions within the SI  units to measure the same physical quantity may look like a very tiring task but it helps a lot to speed up the calculations and accuracy if you’re solving difficult

problems based on unit conversion. You should try to remember these different prefixes and

practice them to master them. We hope that this article helped you in understanding how SI units are important, how units are converted in physics, and also what are different quantities in physics.