IGCSE Physics

Measuring Volume.

The SI unit of volume is m³

A- Volume of regularly Shaped Objects

Volume of some of the regular solids can be calculated using the formulae given in the following table.

Object	Volume(formula)
Cube	(length)3 = L3
Cuboid	length X breadth X height = L x b x h
Cylinder	pi x radius2 x height = pi r2 h
Sphere	4/3 x pi  x (radius)3 = 4/3 pi  r3
Cone	1/3 x pi  x (radius)2 x height = 1/3 pi  r2 h

Note:-

The solid shape must be hard to be measured accurately; if it is made up of clay or something similar will the calculated volume will not be the true volume.

B- Volume of Irregularly Shaped Objects

Volume of irregularly shaped objects can be found out by

i-     Displacement method.

By measuring the volume of displaced liquid by an object. We can find the volume of these solids with the help of a measuring cylinder.

 

Steps:-

a-   Fill the overflow vessel with water until the water start overflowing.

b-   When water stops overflowing, place the measuring cylinder below the overflowing tube.

c-    Slowly lower the irregular solid into the water by a very thin string.

d-   When the water stops overflowing, read the volume of the water collected in the measuring cylinder.

e-   This reading will be the volume of the irregular solid shape.

i-    Measuring cylinder.

 To measure the volume of an irregular body using measuring cylinder

 Steps:-

a-   Pour water into a clean measuring cylinder (nearly three fourth of its volume) and record the level of water (v₁).

b-   Slowly lower the irregular solid into the water by a very thin string.

c-    Measure the new volume of the water and the stone (v₂).

d-   Then calculate the volume of irregular solid shape as

“v= v₂-v₁”

The volume of this stone = ………….

ALSO……
you can use measuring cylinder for sure to measure the volume of liquids.

 

Notice that:-

1. The measuring cylinder must be placed on a horizontal bench.
2. Using large measuring cylinder to measure small amounts, leads to errors in results.
3. You have to avoid parallax error.
4. If the string holding the stone is thick it may cause a reading error or absorb little amount of water.
5. Equal masses of different densities have different volumes

Liquid levels

1. Reading must be taken at the lowest level of meniscus or curved surface of the liquid.
2. Reading must be taken at the top level of meniscus or curved surface of the liquid in case of Mercury.
3. Liquid A is water and liquid B is mercury.