Important Conversions

We convert a unit of measurement into a different unit but with the same property. In physics, we often see questions that ask us to convert between various units. If we take the example of time, we can express it in hours, minutes, and seconds. The distance can be expressed in miles, kilometres, metres, and sometimes in feet. However, we need a conversion factor that ensures that the conversion of one unit to another is an equal exchange. We change one unit of measurement into another by multiplying or dividing it by a number, and that number is known as the conversion factor.

Conversion of Units

Conversion of units is a multi-step process involving operations like multiplying or dividing by a numerical factor, selecting the correct number of digits, and rounding them. E.g., to convert the speed of a car from metre per second to kilometres per hour, we multiply it by 18/5.

Some things people use in their daily lives, such as speed, temperature, time, area, volume, etc., require units of measurement. However, there are incidents when the unit we are using for measurement does not match the measurement we usually use. If we take the example of a car that runs at a speed of 500 feet per minute, you will not be able to imagine its speed. Therefore, we need to convert the speed into kilometres per hour or metres per second.

We can take another example of time. Let’s suppose we have 480 seconds. How much will that be in minutes? One minute equals 60 seconds, so we will divide 480 by 60, and we get our answer, i.e., 8 minutes.

Some other essential conversions that we use in physics are –

Length

We can convert length into a different unit based on our requirements.

• 1 cm = 10 mm

• 1 inch = 2.54 cm

• 1 m = 100 cm

• 1 km = 1000 m

• 1 mile = 1.6 km

We use these units for the measurement of length. If we need to measure the length of a table, we will use metres or feet, not kilometres.

Temperature

Temperature is measured in °F, °C, and kelvin. We need different formulas for temperature conversion from one unit to another.

From Fahrenheit to Kelvin,

K = (°F – 32) / 1.8 + 273.15

From Celsius to Fahrenheit,

°F = °C (1.8) + 32

From Celsius to Kelvin

K = °C + 273.15

There are many more formulae for the conversion of temperature. We can use any of them according to our needs.

Area

We use the area to measure the surface of a two-dimensional body. E.g. the area of a rectangular land is 1200 square feet.

• 100 mm2 = 1 cm2

• 10000 cm2 = 1 m2

• 1000000 m2 = 1 km2

Energy

The capacity of doing work is termed energy. It has many forms and units as well. Conversion of its units are –

• 1 Joule = 107 ergs

• 1 Kilowatt hour = 3.6 x 106 Joule

• 1 Kcal = 4186 kJ

• 1 Wh = 3.6 J

Mass

Mass can be defined as the number of atoms present in a body.

1 kilogram = 1000 grams

1 gram = 1000 milligrams

1000 kilogram = 1 ton

1 quintal = 100 kilograms

International System of Units

The international system of units was made in 1960 and was updated from time to time. This system aims to provide a standard value for measurements regardless of where these units are used in the world. In physics, we have SI units for area, volume, length, mass, force, temperature, energy, etc. This system of units ensures uniformity in measuring quantities. It can be used in trade and commerce, procurements, and other business-related activities. 

Conclusion

Conversion of a unit of measurement is often required to solve a problem. At times the conversion of the unit could be more important than solving the problem. Converting units is not a single-step process. Instead, it requires operations like multiplication and division. If we talk about quantities, the units play an important role in describing the value of the physical quantity required. For instance, if someone went to buy a rope, how is he supposed to tell the salesman the amount of rope he wants? These are some of the reasons we need appropriate units of measurement.