Page 122 - Innovator's Science-8

Determining Volume of Objects with Irregular Shapes

To find the volume of an object that has an irregular shape, like a stone, we
can use the water displacement method . First, fill a measuring cylinder
with water and record the starting water level. Then gently put the stone
into the cylinder, making sure it is completely underwater. The water level

will rise because the stone pushes some water out of the way—this rise
Science indicates the volume of the water displaced, which equals the volume of
Bytes
the stone. To figure out the stone's volume, subtract the starting level of

Testimony the water from the final level after the stone is in. The difference is the
The water displacement volume of the object, measured in milliliters (which is the same as cubic
method works on the
principle discovered by centimeters). This method works well for any small solid that doesn't have
Archimedes. When an a regular shape. You can understand it through an activity.
irregular solid is fully
immersed in water, it Collect various objects from your surroundings, such as a stone, metal keys,
pushes out (displaces) an and so on.
amount of water equal to
its own volume. Fill a measuring cylinder with water up to any desired volume, say 50 mL
This simple idea allows us and record the initial volume taken. Suppose the volume of water is 50 mL.
to measure the volume of
objects that cannot be Tie the object, like a stone, with a thread and slowly lower it into the
measured with a scale or measuring cylinder.
formula.
What do you notice?
Record the final volume after the level rises; say 55
mL, as shown. Subtract the initial volume from the

final volume after the object is put into the
measuring cylinder. This is the volume of the object.

Record your observation in the given table.

Volume of irregular solids
Ini al volume Final volume Volume of water Volume of the
S.No. Object 3
of water in the of water in the displaced object (cm )
measuring cylinder measuring cylinder (mL) (B-A)
(mL) (A) (mL) (B)
1. Stone 50 mL 55 mL 5 mL 5 cm 3

2. Metal key
3. Any other

We have already learnt to measure the mass and volume of liquids and
solids of different types. These quantities can be used to calculate the

density of the object or the substance. Let us calculate the density.

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