Intro to Mass and Volume

I. Mass

Mass is defined as the amount of matter present in a body. The SI unit of mass is the kilogram (kg).

Note: The mass of a body is constant; it does not change at any time. Only in certain extreme cases when a huge amount of energy is given or taken from a body, the mass may be impacted. 

There are various units for calculating mass, like, kilograms, grams, pounds, etc., but the SI unit of mass is 'kilogram' or kg. Note: 1kg is equal to 2.20462 pounds.

Kilo = 1000

Therefore

1000 grams = 1 kilogram

Here are some various objects to get a sense of weight in grams and kilograms.

paper clip ≈ 1g

pencil ≈ 5g

mouse ≈ 20g

kitten ≈ 200g - 300g

text book ≈ 1kg

cat ≈ 3kg - 5kg

adult person ≈ 60kg - 80kg

cow ≈ 750kg

Difference Between Mass and Weight

People often get confused between mass and weight and they end up using these two terms interchangeably. However, mass and weight are two different terms and it is important to understand the difference between them. The difference between mass and weight is shown in the table given below.

	Mass	Weight
Definition	Mass is defined as the amount of matter in a substance	Weight is defined as the amount of force acting on the mass of an object because of acceleration due to gravity.
Denotation	Mass is represented by 'M'	Weight is represented by 'W'
Formula	•Mass is always constant for a body. •One way to calculate mass: Mass = volume × density	•Weight is the measure of the gravitational force acting on a mass. •Formula of weight: Weight = mass × acceleration due to gravity
Unit of Measurement	The SI unit of mass is 'kilogram'	The SI unit of weight is Newton (N).
Quantity Type	•Mass is a base quantity. •Mass only has magnitude and hence, it is a scalar quantity	•Weight is a derived quantity. •Weight has both magnitude and direction (toward the center of gravity) and hence, it is a vector quantity.
Measuring Instrument	Mass can be easily measured using any ordinary balance. For example, beam balance, lever balance, pan balance, etc.	Weight can be measured by a spring balance or by using the formula given above.

Did you know that we have different weights on the Earth, the Moon, and in space? However, our mass is the same everywhere.

II. Volume

Volume is defined as a capacity occupied by a three-dimensional solid shape. We learned that for calculating the area of any two-dimensional shape, we divide the portion into equal square units. Similarly, when calculating the volume of solid shapes we will divide it into equal cubical units.

Volume of a Cuboid

Suppose we have some rectangular sheets with length 'l' and width 'b'. If we stack them one on top of the other up to height 'h', we get a cuboid of dimensions l, b, h. This can be seen in the following figure which shows the length, width (breadth), and height of the cuboid thus formed.

To calculate the amount of space enclosed by this cuboid, we use the formula: Volume of a Cuboid = l × b × h

Unit of Volume

The S.I. unit of volume is cubic meter (m³) since volume is a quantity of the three-dimensional space occupied by a shape or surface. However, the most commonly used unit for volume is liter.

Milli = 1/1000

Therefor 

1000 milliliter = 1 liter

Here are some things to get a sense of volume in milliliters and liters.

20 drops ≈ 1 ml

teaspoon of water ≈ 5 ml

bottle of milk ≈ 1 l

Olympic size swimming pool ≈ 2,500,000 l

Reference

Cuemath: Mass
Khan: Understanding mas (grams and kilograms)

Cuemath: Volume

https://www.cuemath.com/measurement/length-width-height/