This unit is about Volume in Ordinary Level Physics with relative diagrams.


This is defined as the amount of space occupied by an object. Volume is measured in cubic units eg m3, cm3, mm3 e.t.c

Calculate the volume of the cylinder.

volume 4

Given that a cuboid has sides:

20cm by 10cm by 15cm


The surface area in cm2.

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2 [l x h + l x w + w x h]

2 [20 x 15 + 20 x 10 + 10 x 15]

2 [300 + 200 + 150]

2 x 650

= 1300cm2

volume 7

volume 8


To obtain the volume of an irregular object, we use displacement method. The following instruments are used to measure the volume;-

Solid objects;-e.g. a stone, egg excreta;-

– An overflow can

– A measuring cylinder

– A thread

– Water

– Beaker

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– Place a beaker below the spout of the Eureke can

– pour water in the Eureke can, leaving the excess to flow in to the beaker below the spout.

– Leave the water to settle at spout level, and then remove the beaker.

– replace the breaker with a measuring cylinder

– tie a string tightly around the irregular objects.

– Lower it gently into the water in the Eureka can.

– leave the water to flow into the measuring cylinder and after it has settled record the reading of the water in the measuring cylinder.

This is the volume of the displaced water. The volume of the irregular object is equal to the volume of the displaced water.

The volume of small objects may also be determined using the measuring cylinder as follows.


– String

– Water

– measuring cylinder

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– place the measuring cylinder on a flat surface

– Pour water in the measuring cylinder to a reasonable level and record the reading [v1cm3] taken at the bottom of the meniscus.

– Tie a string tightly around the irregular object

– Hold the irregular object by the string and lower it gently into the water

– Record the reading [v2cm3] after the water has settled.

– Calculate the volume of the displaced water i.e.

Volume of displaced water = [v2-v1] cm3

Volume of irregular object = volume of displaced water

= [v2-v1] cm3

The volume of liquids can also be obtained using a way of the instruments below;-

Measuring cylinder

volume 13

volume 14


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