Chapter 14: Heat and Temperature

flinkexistenceMechanics

Oct 27, 2013 (4 years and 2 months ago)

77 views

Chapter 14: Heat and
Temperature

Section 1: Temperature

Key Ideas


What does temperature have to do with
energy
?

Temperature


A
measure of how hot (or cold) something
is


average
kinetic energy of the particles in an
object

Thermometers


An
instrument that measures and indicates
temperature



As liquids (such as mercury) get hotter, they
expand in volume.


As the liquid in a thermometer expands, it moves
up the tube of the thermometer, showing us the
temperature.

Temperature Scales


3 most common
temperature scales:


Fahrenheit


C
elsius


kelvin

Energy Transfer Causes
Temperature
C
hange


T
ransfer of energy is
always from something
at a higher
temperature to
something at a lower
temperature.


Heat: E
nergy
transferred between
the particles of two
objects.

Section 2

Energy Transfer

Key Ideas


How does energy transfer happen?


What
do conductors and insulators do
?

Methods of Energy Transfer


Heat energy can be transferred in three ways:



Conduction


Convection


Radiation

Conduction


the transfer of energy as heat through a
material

Convection


Convection current: circular
movement of matter that
results from differences in
density

Radiation


the energy that is
transferred as
electromagnetic waves,
such as visible light and
infrared
waves


Does not require
physical contact
between objects

Conductors and Insulators


C
onductor:
transfers heat well


Insulator
:
transfers heat poorly

Section 3

Using Heat

Key Ideas


What happens to heat energy when it is
transferred?

Laws of Thermodynamics


F
irst law of thermodynamics:

total energy
used in any process is conserved, whether
that energy is transferred as a result of work,
heat, or both.


S
econd law of thermodynamics:

energy
transferred as heat always moves from an
object at a higher temperature to an object at
a lower temperature.

Work and Kinetic Energy


M
echanical processes:
when energy is
transferred by work


Example: When you rub your hands together, they
become warmer. The energy that you transfer to
your hands by work is transferred to the
molecules of your hands, and the temperature of
your hands increases.

Heat Engines


a machine that transforms heat into
work
(
chemical energy is converted to mechanical
energy) through the process of combustion.


Two main types of heat engines


Internal
-
combustion engines


Engines in cars and trucks


external
-
combustion engines


steam engine