Page 97 - Physics

Density and relative density

ICT corner

Visit https://phet.colorado.edu select the simulation titled density
and buoyancy to help students visualise and demonstrate the concept
of density of a substance.

Chapter summary measure the masses and volumes of
1. Density of a substance is expressed different sized samples of a type of
as the mass of the substance per unit wood. Furthermore, they plotted the
volume. Its SI unit is the kilogram graph based on the data collected
3
per cubic metre, kg/m . It can be shown in Figure 4.11. Which graph
m
expressed mathematically as ρ = V ⋅ depict their results?
2. The determination of the density of (a) (b)
a solid depends on the shape of a
particular solid. That is, whether the mass mass
solid has a regular or irregular shape.
3. The density of solids is generally O volume O volume
higher than the density of liquids. (c) (d)

4. Relative density of a substance is the
ratio of the substance’s density to the mass mass
density of water. It has no units since
it is a ratio of the same quantity. O volume O volume
Figure 4.11
5. A relative density bottle is used to
determine relative density of liquids. (ii) What is the density of the liquid in

6. Density is used in designing various Figure 4.12?
structures for ships and aircraft. cm 3 50 cm 3 50

7. Density is considered during the 40 40
selection of building materials and 30
design of swimming equipment. 30
20 20

Revision exercise 4 10 10
Section A
200g 250g
1. Choose the most correct answer.
Figure 4.12
(i) A group of Form One students
3
3
conducted an experiment to (a) 0.5 g/cm . (c) 8.0 g/cm .
3
3
determine the density of wood. They (b) 2.0 g/cm . (d) 10.0 g/cm .
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