Page 94 - Physics

Physics for Secondary Schools

Example 4.8 Relative density of a liquid can be
determined using the following
A block of metal has a mass of 264 g. procedure:
The block is totally immersed in water 1. Find the mass of an empty bottle, m .
fi lling up a eureka can. If 24 g of water 0
overfl ows through the spout of the can 2. Fill in the bottle with the liquid and
into a beaker, calculate the relative measure the mass of the bottle with
density of the metal. its contents. Record this mass as m .
1
3. Empty the bottle, clean and dry it
Solution;
Mass of a metal = 264 g thoroughly.
Mass of equal volume of water = 24 g 4. Fill in the bottle with water and
Mass of substance measure the mass of the bottle
Relative density =
Mass of equal volume of water containing water. Record this mass
264 g m .
= = 11 2
24 g Hence, mass of liquid = ( m − m ) g
The relative density of the block is 11. 1 0
Mass of an equal volume of water =
( m − m ) g
2
0
Determination of relative density of
a liquid R.D = Mass of substance
Mass of an equal volume of water
The relative density of a liquid can be m - m
determined using a relative density bottle = m 1 - m 0 .
shown in Figure 4.8. A bottle is fi tted 2 0
with a stopper made of ground glass
having a narrow hole. The hole enables Acti vity 4.7
air to escape from the bottle when it is Aim: To determine the relative
being fi lled with a liquid. density of cooking oil.

Materials: Relative density bottle,
cooking oil, beam
balance and water

m m m
0 1 2

Figure 4.9:
Figure 4.8: Relative density bottle

88
Student’s Book Form One

Physics Form 1 Final.indd 88 16/10/2024 20:56