Page 95 - Physics

Density and relative density

Example 4.9
Procedure
1. Measure the mass of an empty In an experiment to determine the relative

relative density bottle with its density of liquid X, Form One physics
stopper. Record the mass as m . students obtained the following results
0
2. Fill in the bottle with cooking oil, after various measurements.
replace the stopper and wipe out any Mass of an empty relative
excess liquid. Measure the mass. density bottle = 15 g
Record the mass as m . Mass of bottle + liquid X = 35 g
1
3. Replace the cooking oil with water Mass of bottle + water = 40 g
and measure the mass. Record it as Volume of bottle = 25 cm 3
m .
2
Calculate,
Questions (a) The density of water in kg/m .
3
(a) Calculate the relative density of
3
cooking oil. (b) The density of liquid X in kg/m .
(b) What is the signifi cance of a narrow (c) The relative density of liquid X.
hole in the relative density bottle? Solution
(a) Mass of water 40 g – 15 g = 25 g

Volume of water = 25 cm 3

The relative density of cooking oil can Density of water = 25 g = 1 g/cm 3
be obtained by: 25 cm 3

(i) Finding the mass of cooking oil, Density of water in kg/m = 1 000 kg/m .
3
3
( m − m ).
1
0
(b) Mass of liquid X = 35 g – 15 g
(ii) Finding the mass of an equal = 20 g
(
volume of water, m − m ) g. . Volume of liquid X = 25 cm 3
0
2
(iii) Calculating the relative density Density of liquid X = 20 g
25 cm 3
m  m
of cooking oil, 1 0 . = 0.8 g/cm 3
m  m 0
2
3
3
(iv) The narrow hole in the stopper Density of liquid X in kg/m = 800 kg/m .
enables air to escape from the (c) Relative density of
bottle when it is being fi lled with

a liquid. liquid X = 800 kg/m 3 = 0.8.
1 000 kg/m 3

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Physics Form 1 Final.indd 89 16/10/2024 20:56