Learn And Convert The Basic Units of Mass Length & Time

How far is my city from another city is measured in mile or kilometer. How heavy is the box of apples is measured as gram or kilogram. How much time the train takes from one city to another city is measured in minutes or hours. So, the mile, kilometer, gram, kilogram, minutes and hours are the units which is used to measure quantities.

There are many more units available in science and mathematics to measure quantities, few of the examples are temperature measured in celsius or fahrenheit, volume in liter, angles in degrees, area in square meter and volume in cubic meter.

This chapter primarily introduces the following concepts:

Which are the basic units that are used in day to day measurements?
Which are the things that we can measure and assign units to them?
How to convert units into one another using the conversion tables?

Units

Unit is a standard that is used to measure quantities. For example, the quantity length is measured in centimetres, so centimetre is called a unit of length. Mass of an object is measured in kilograms, so kilogram is the unit of mass. Time is measured in seconds, so seconds is a unit of time.

These units are placed next to the number value of the quantity measured, for example the distance between two cities is 10 kilometers, where 10 is the number value and kilometer is the unit.

There are short forms available for all units. The short form of centimeter is cm, for kilogram it is kg and short form of second is only "s".

Table of units of quantities
Quantity	Name of unit	Symbol of unit
Length	Meter	m
Mass	Kilogram	kg
Time	Seconds	s

The above table shows only one unit of length, mass and time, but there are more units available to measure these quantities. The following tables list more units of length, mass and time.

Units of length

Table of units of length
Name of unit	Symbol of unit
Meter	m
Centimeter	cm
Millimeter	mm
Kilometer	km
Miles	mi
Yards	yd
Foot	ft
Inch	in

Units of mass

Table of units of mass
Name of Unit	Symbol of Unit
Kilogram	kg
Gram	g
Milligram	mg
Pounds	lbs
Ounce	oz

Units of time

Table of units of time
Name of Unit	Symbol of Unit
Hour	hr
Minute	m
Second	s

Measure quantities

How do the units help in measuring quantities? Is every unit of length used to measure the same length of distance?

All types of units of length are not meant to measure the same distances. Some distances can be longer like distance between two cities and some can be shorter like the length of a pencil.

The different units are meant to measure quantities depending upon if the quantity is big or small.

Length

To measure lengths like the distance between two cities, which is very long, the unit kilometer is used for this purpose

To measure short lengths like the length of a pencil, which is a short length of the size of a hand, is measured in centimetres.

Generally, kilometer and miles milestones can be seen on both sides of the road while travelling. The milestones tell how far is the destination city, which in fact tells the longer distances.

The following table shows which units are best suitable to measure the lengths.

Table of units used to measure lengths
Quantity	Best suitable units
Distance between two cities	kilometer
Length of a car	meter
Height of a person	centimeter, meter

Mass

Heavy things like a big box of bananas are measured in kilograms and things with less weight like a pencil are measured in grams.

Table of units used to measure mass
Quantity	Best suitable units
Mass of person	kilogram
Mass of toothpaste	gram
Mass of big box of bananas	kilogram

Time

Long durations of time like the number of vacations are counted in days not in hours. Hours or minutes or seconds is used to measure shorter durations like cooking time to cook a cake in minutes.

Table of units used to measure time
Quantity	Best suitable units
Time to travel one country to another	hour
Time to start a car's engine	second
Time to walk to next door market	minute

Unit conversions

To convert units, you need to know a unit conversion value, e.g. 1 m = 100 cm, it says one unit of meter is equal to 100 centimeter. So, this is a unit conversion of 1m into centimetres.

Example of converting units of length

Which is bigger, 2 m or 2 cm?

Convert 2 m into centimeter units

We know that 1 m = 100 cm

2m can be written as 2 × 1 m

Therefore, 2 m = 2 × 1 m = 2 × 100 cm = 200 cm

2 m = 200 cm

Now, 2 cm and 200 cm can be compared to find the biggest. 200 cm is clearly bigger than 2 cm.

Conversion tables

Table of length

Length conversion table is an excellent tool that helps convert the units of length into each other.

Conversion table for length

Meter units of length in kilo, hecto, deca, deci, centi and milli

In the conversion table we can move in the left or right direction. Move right to convert kilo into centi, move left to convert deci into hecto. Then, we count the number of positions we move from left to right or right to left.

We add that much number of 0s next to 1 and make numbers like 10, 100, 1000 or 10000 etc. If the movement is from right to left then the unit to be converted is multiplied by this number and if the movement is from left to right then the unit number is divided by this number.

Table of mass

The following figure shows the conversion table to convert units of mass. The steps to convert units of mass are the same as those are explained in Conversion of units of length.

Conversion table for mass

Gram units of mass in kilo, hecto, deca, deci, centi and milli

Table of volume

The following figure shows the conversion table to convert units of volume. The steps to convert units of volume are the same as those are explained in Conversion of units of length.

Conversion table for volume

Litre units of volume in kilo, hecto, deca, deci, centi and milli

Convert units

Conversion of units is a process of converting one unit into another unit. Conversion can only be carried on the same type of quantities. For example, a length unit can be converted to another unit of length.

Conversion of units from one to another unit never changes. The magnitude of measurement of a quantity remains the same, only the units are changed. Conversions are used in solving problems of comparing the measurements.

Example of converting units

Convert 20 kilometers into centimeters.

Step 1: Find the direction of movement.

Here, we need to change kilo into centi, so the direction of movement is left to right.

Step 2: Find the number of positions to be moved.

The starting point is kilo and the end point is centi. So, we start counting after hecto as Ist position, then deca as 2nd position, meter as 3rd position, deci as 4th position and centi as 5th position. The total number of positions moved are 5 from kilo to centi.

Step 3: Make the conversion number.

So, the conversion number is formed by adding the number of 0s next to 1 and the number of 0s are equal to the number of positions moved.

i.e. conversion number = 100000

Step 4: Multiply the old unit with the conversion number to get new units because we moved from left to right.

New units = 20 × 100000 = 2000000 centimeter

Convert 6 meters into hectometers.

Step 1: Find the direction of movement.

Here, we need to change the meter into hecto, so the direction of movement is right to left.

Step 2: Find the number of positions to be moved.

The starting point is the meter and the end point is hecto. So, we start counting after deca as Ist position, then hecto as 2nd position. The total number of positions moved are 2.

Step 3: Make the conversion number.

i.e. conversion number = 100

Step 4: Divide the old unit with the conversion number to get new units because we moved from right to left.

New units = $\frac{6}{100}$ hectometer

List of more units

Area

In geometry we come across many measurements that need area calculations like area of circle, surface area of sphere or area of lawn and there are many such examples. So, area is quantity that is measured in units of metre square m² or centimeter square cm².