WEEK 6 PHYSICS CLASS

The real ( or absolute) cubic expansivity of a liquid is the
increase in volume per unit volume per degree rise in temperature

The apparent cubic expansivity of a liquid is the increase in
volume per unit volume per degree rise in temperature when the
liquid is heated in an example vessel

To determine the apparent cubic
expansivity of a liquid

Example
A density bottle 250g of liquid at 30oc and only 248.5 g at 60oc.
Find
a.

The apparent and

b.

The real cubic expansivity of the liquid, if the linear expansivity
of the material of the bottle
Is 0.000006K-1

CHANGE OF STATE

Solid can change to liquid and to

vapour and vice versa

FUSION( OR MELTING)

Is the process whereby a substance changes from solid state to a liquid state when heat is
applied to it.

VAPORISATION

Is the process by
which a substance
changes from a
liquid to a gaseous
state when heat is
applied to it.
LINK.( Third
explanation)

Factor affecting the Rate of Vaporization

1.

Temperature:

2.

Surface area:.

3.

Pressure:.

4.

Wind speed:

Examples of Vaporization in Our Daily Life

● Industrially, salt is recovered from sea-water

by the process of vaporization.

● Wet clothes are dried up due to the process of

vaporization.

● The process is used in many industrial processes

for separating the components of a mixture.

The process
where a liquid
turns into
vapour before
its boiling point
is known as
evaporation

BOILING

Boiling is defined as a phase
transition from the liquid state
to the gas state, usually
occurring when a liquid is heated
to its boiling point. At the
boiling point, the vapor pressure
of the liquid is the same as the
external pressure acting upon its
surface.

TRANSFER OF HEAT
CONDUCTION

Conduction of heat is the process by which heat energy is transferred through a material,
the average position of the particles of the material remaining the same.

The ability of a metal to conduct heat is know as its THERMAL CONDUCTIVITY.

CONVECTION

Convection is the process by which heat transferred in a liquid or gas by the actual
movement of the fluid from the hotter to the colder parts.
Convection currents in Gases
Convection current in Nature: land and sea breezes.

RADIATION

Radiation is the process by which heat is transferred from a hotter to a cooler place
without heating of the intervening medium.