Transcript Energy - CPALMS.org

What temperature does
the thermometer
indicate?
The temperature
hovers at zero
Celsius.
Essential Question
Understanding
how
does heat affect a
system?
What does it mean to have
a temperature of 0 C?
What is temperature?
Is temperature the same
thing as heat?
So what is heat?

Heat is the amount of thermal
energy. For example, the sparks
from a sparkler are at around
800°C but do not burn your skin.
However, a hot cup of tea at
around 100°C will burn your
hand badly. This is because the
tea contains more heat energy,
even though it is cooler.
Temperature is a measure of
how “hot” or “cold”
something is.
Temperature is measured in
arbitrary units, like
Fahrenheit or Celsius.
Units of Temperature
between Boiling and Freezing
Nature of Energy

Energy is all around you!
 You can hear energy as
sound.
 You can see energy as light.
 And you can feel it as wind.
Nature of Energy

What is energy that it can be
involved in so many different
activities?
 Energy can be defined as the
ability to do work.
 If an object or organism does
work (exerts a force over a
distance to move an object) the
object or organism uses energy.
Forms of Energy
The
five main forms of
energy are:
 Heat
 Chemical
 Electromagnetic
 Nuclear
 Mechanical
Nature of Energy
 Because
of the direct connection
between energy and work,
energy is measured in the same
unit as work: joules (J).
 In addition to using energy to do
work, objects gain energy
because work is being done on
them.
Heat Energy/THERMAL
ENERGY
The internal motion of the atoms is
called heat energy, because moving
particles produce heat.
 Heat energy can be produced by
friction.
 Heat energy causes changes in
temperature and phase of any form
of matter.
 Energy of the heat IN an object

States of Energy
 The
most common energy
conversion is the conversion
between potential and kinetic
energy.
 All forms of energy can be in
either of two states:
 Potential
 Kinetic
Heat is the thermal energy
transferred from a hot
object to a cold object.
Heat is measured in
energy units -Joules or calories.
Is heat absorbed or
released during a phase
change?
We know that heat is either
absorbed or released during
a phase change.
Heat is absorbed as
solids melt, or liquids
vaporize.
Heat is released as liquids
freeze, or vapors condense.
Heat is absorbed by
the ice.
Ice
And melts
Heat is absorbed by
the ice.
One gram of ice at 0C
absorbs 334 J as it
melts to form water at
0C.
… making liquid water
Heat is
released by
the water
as it
freezes.
334 joules is
Ice
water
released when one
gram of water
freezes at 0C.
Ice absorbs 334 J per
gram as it melts at
0C
Ice
Water releases 334 J per
gram as it freezes at 0C
Heat is absorbed
by the water as it
vaporizes.
Hotplate
Heat is absorbed
by the water as it
vaporizes. 2260 joules is
Hotplate
absorbed by
one gram of
water as it
boils at 100C.
Steam
releases
2260
J/g as it
condens
es at
100 C
Water
absorbs
2260
J/g as it
boils at
100 C
Hotplate
Heat is released by
water vapor as it
condenses.
Heat is released by
water vapor as it
condenses.
The heat released by
condensing water vapor is a
major factor in weather
phenomena like
thunderstorms and
Phase changes
occur at a
constant
temperature as
heat is
absorbed or
Question for discussion:
If phase changes occur
at a constant
temperature, then
what happens to the
heat when water boils?
The heat energy breaks the
intermolecular bonds which
keep the water in the liquid
phase.
States of Energy:
Kinetic and Potential Energy
Kinetic
Energy is the
energy of motion.
Potential Energy is
stored energy.
Kinetic Energy




The energy of motion is called
kinetic energy.
The faster an object moves, the
more kinetic energy it has.
The greater the mass of a moving
object, the more kinetic energy it
has.
Kinetic energy depends on both
mass and velocity.
Potential Energy

Potential Energy is stored energy.
 Stored chemically in fuel, the nucleus
of atom, and in foods.
 Or stored because of the work done on
it:
 Stretching a rubber band.
 Winding a watch.
 Pulling back on a bow’s arrow.
 Lifting a brick high in the air.
Gravitational Potential Energy
 Potential
energy
that is
dependent on
height is called
gravitational
potential
energy.
Potential Energy

Energy that is stored due to being
stretched or compressed is called
elastic potential energy.
The Law of Conservation of Energy

Energy can be neither created nor
destroyed by ordinary means.


It can only be converted from one form
to another.
If energy seems to disappear, then
scientists look for it – leading to many
important discoveries.
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