Time Measurement and Measuring Devices

# Unit conversion

Conversion from one unit of a quantity to another is a common activity that is often come across when carrying out measurements or calculating in science.

Example

The example is available to registered users free of charge.

According to the example above, conversion of units is therefore needed. So, we either convert 2 m to cm or 500 cm to m before adding the two values.

## Meaning of unit conversion

Physical quantities usually have more than one unit. Therefore, there is sometimes the need to convert from one unit of the quantity to another, most importantly, to the SI unit of the quantity.

Unit conversion is a step-by-step process of converting between different units of measurement of the same quantity.

This usually involves multiplication or division by a conversion factor.

The conversion factor used in converting from one unit to another depends on the prefixes before the units.

## SI prefixes

The SI units usually have prefixes, which indicate the powers of 10 by which a unit may be multiplied.

Example

The example is available to registered users free of charge.

Prefixes are written with the SI unit name or symbol to form what are called multiples and submultiples of the unit.

The prefixes with their symbols and multiplying factors are shown on the table below:

 Prefix name Prefix symbol Multiplying factor yocto zepto atto femto pico nano micro milli centi deci / / deka hecto kilo mega giga tera peta exa zetta yotta

From the table above, we can therefore obtain the conversion factors for converting between units.

The following steps can be taken to obtain the conversion factor for converting between two units:

• Step 1: We identify which prefix is smaller and which is bigger.

• Step 2: We identify the multiplying factor of each prefix.

• Step 3: We identify the starting prefix and the required or the desired prefix.

• Step 4:

• To convert from the smaller prefix to the bigger prefix, we simply subtract the power of the bigger prefix from that of the smaller prefix.

• To convert from the bigger prefix to the smaller prefix, we simply subtract the power of the smaller prefix from that of the bigger prefix.

Let's look at some examples.

Example

The example is available to registered users free of charge.

Therefore, to convert the value of a quantity from one unit to another, we take the following steps:

• Step 1: We identify the given or starting unit.

• Step 2: We identify the required or desired unit.

• Step 3: We obtain the conversion factor for converting from the given unit to the desired unit.

• Step 4: We multiply the given value by the conversion factor obtained in step 3.

• Step 5: We express the result in the scientific notation if necessary.

Unit conversion is a step-by-step process of converting between different units of measurement of the same quantity. This usually involves multiplication or division by a conversion factor.

The SI prefixes indicate the powers of 10 by which a unit may be multiplied.

The value of a quantity can be converted from one unit to another by taking the following steps:

• Identify the given or starting unit.

• Identify the required or desired unit.

• Obtain the conversion factor for converting from the given unit to the desired unit.

• Multiply the given value by the conversion factor obtained in step 3.

• Express the result in the scientific notation if necessary.

Let's see some examples:

Example

The example is available to registered users free of charge.

Therefore, is equal to .

Example

The example is available to registered users free of charge.

Therefore, is equal to .

Example

The example is available to registered users free of charge.

Therefore, is equal to .

• Do not round off any value within the calculation.

• Only round off the final result.