How Big How Heavy - Measuring Weight and Capacity

Volume is the total amount of space occupied by a three-dimensional object. Imagine a hollow box; the amount of space inside it that can be filled with air or water is its volume.

The basic unit of volume is the cubic centimeter, written as $1 cm^3$. Visually, this is a tiny cube where the length, width, and height are all exactly $1 cm$. For larger objects, we use cubic meters ($m^3$).

A cuboid is a 3D shape like a shoebox or a brick. To find its volume, you must consider three dimensions: Length (how long it is), Breadth (how wide it is), and Height (how tall it is).

A cube is a special cuboid where all sides are equal, like a playing die. Since the length, breadth, and height are the same, we simply multiply the side by itself three times.

Capacity is a term used for the volume of liquids a container can hold. While solid volume is measured in $cm^3$, liquid capacity is measured in Liters ($L$) and Milliliters ($mL$). Think of a large milk packet as $1 L$ and a small medicine dropper as holding $1 mL$.

The displacement method is used to measure the volume of irregular objects like stones. When you drop a stone into a measuring jar filled with water, the water level rises. The volume of the displaced (risen) water is exactly equal to the volume of the stone.

Weight measures how heavy an object is using units like grams ($g$) and kilograms ($kg$). In many contexts, $1 mL$ of water has a mass of approximately $1 g$, and $1000 mL$ (or $1 L$) of water weighs approximately $1 kg$.