Page 123 - Innovator's Science-8

Density can be calculated using the following formula:
Mass
Density=
Volume
16.400/5= 3.28 g/cm 3

Crust Earth is made up of several layers, each one lying deeper beneath
Mantle
the one above it and having a different density. The outermost
Outer
core layer, called the crust , is the lightest and thinnest. As we move
Inner deeper, we reach the mantle , then the outer core , and finally the
core
inner core at the very center. The deeper the layer, the denser it
is; in other words, the materials inside Earth become heavier and

more tightly packed as you go down. This happens because both
the pressure and the temperature increase the deeper you go,
Layers of Earth
squeezing materials together, making them heavier and more compact.

Science Effect of Temperature on Density
Bytes
Generally, the density of a substance decreases with heating and increases
Testimony with cooling. This can be explained on the basis of what you have learnt in
Take a glass tumbler and chapter 'Particulate Nature of Matter'. As temperature increases, the
fill it with tap water.
Carefully place a raw particles of a substance whether, solid, liquid, or gas, tend to move away and
whole egg into the water spread. This results in an increase in volume but there is no change in mass.
and observe what
happens. You will no ce Since the Density = Mass/Volume, upon heating, the volume increases and
that the egg sinks to the the density decreases. This explains why hot air moves up as it is less dense
bo om. What change can than the cool air around it. The hot air balloon works on the same principle.
you make to this setup to
make the egg float in Effect of Pressure on Density
water instead of sinking?
It happens due to the Pressure affects the density of different states of matter in different ways. For
density.
gases, when pressure increases, the gas particles are pushed closer together,
which reduces the gas’s volume and makes its density higher. In liquids,
pressure has much less effect because liquids are almost incompressible,
meaning their volume doesn’t change much. Solids are even less affected by
pressure because their particles are already packed tightly, so their density

changes very little when pressure is applied. In summary, pressure can
greatly increase the density of gases, slightly affect liquids, and hardly
change solids' density at all.

Know Your Scientist
Archimedes (287-212 BCE) was a Greek mathematician and physicest beset known for discovering the
principle of huoyancy, now called Arclimedies’ Principle. While stedying how objects float or sink in water, he
realised that an object immersed in a fluid experiences an upward force equal to the weight of the fluid it
displaced. This discovery laid the foundation for understanding density and flotation. Archimedes also made
lasting contributions to geometry, mechanics, and innovations such as Archimedean screw for raising water.

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