Transcript 3.2 “Conserving” Energy

Physical Science
and You
• Chapter One: Studying Physics and Chemistry
• Chapter Two: Experiments and Variables
• Chapter Three: Key Concepts in Physical
Science
Chapter Three: Key Concepts in
Physical Science
• 3.1 Mass and the Atomic Theory of
Matter
• 3.2 Temperature and Energy
Investigation 3B
Mass and Indirect Measurement
• How do scientists measure things too small to
put on a balance?
How do we measure tiny objects
such as a single grain of rice?
3.2 Systems
• In science, the
word “system”
means a group of
related things that
work together.
What part in our optical system
controls the amount of light
entering the eye?
3.2 Energy
• The parts of a system interact with each
other by exchanging energy.
Where does our eye get the energy it
needs to open or close the pupil?
3.2 Energy
• Energy causes change.
• Some changes that occur in systems
include:
1.
2.
3.
4.
5.
temperature
speed
position
mass
other physical variables
What changes can take place in this system?
3.2 Force
•
•
Force is a fundamental quantity in physical
science.
In the metric system, force is measured in
newtons (N).
Would more or less force be needed to pull 2 books?
3.2 Energy
•
•
The unit of energy is related to the units for
force and distance.
One joule (J) of energy is enough to pull with
a force of one newton for a distance of one
meter.
3.2 Potential Energy
• Some objects may have
energy due to their height.
• This kind of energy is
called potential energy
and comes from Earth’s
gravity.
3.2 Kinetic Energy
• Objects in motion
have energy due to
their speed.
• Energy of motion is
called kinetic energy.
3.2 Temperature
• Temperature is the
measurement we use to
make the sensations of hot
and cold more precise.
• A thermometer is an
instrument used to accurately
measure temperature.
3.2 Fahrenheit
• Gabriel Fahrenheit, a
German physicist, was the
first person to use a mercury
thermometer.
• The Fahrenheit scale was
standardized so that the
freezing point of water is 32
degrees and the boiling point
is 212 degrees.
3.2 Celsius
• Anders Celsius, a
Swedish astronomer,
invented a temperature
scale in which there were
100 degrees between
freezing and boiling.
3.2 Extreme Temperatures
• Absolute zero is -273°C.
• You cannot have a temperature lower than
absolute zero.
• Think of absolute zero as the temperature
at which atoms are “frozen.”
3.2 Extreme Temperatures
• Scientists experiment with temperatures as
low as billionths of a degree above
absolute zero and as high as 100 million
million degrees Celsius.
3.2 Heat and thermal energy
• Temperature measures a
kind of energy called
thermal energy.
• Thermal energy comes
from the motion of atoms
in matter.
• We call thermal energy
that is flowing heat.
3.2 Heat and thermal energy
• Thermal energy is often measured in
calories.
• One calorie is the amount of energy it takes
to raise the temperature of one milliliter of
water by one degree Celsius.
3.2 Specific heat
• The specific heat is a
property of a substance
that tells us how much
heat is needed to raise
the temperature of one
kilogram of a material
by one degree Celsius.
Knowing the specific heat of a material tells you how quickly
the temperature will change as it gains or loses energy.
3.2 Conservation of Energy
• The law of conservation of energy says
that energy can never be created or
destroyed, just converted from one form
into another.
• The law of conservation of energy applies
to all forms of energy.
3.2 “Conserving” Energy
We may be running out
of certain “forms” of
energy that are easy or
inexpensive to use.
• Electric power plants do not
make electrical energy.
• Power plants convert other
forms of energy (chemical,
solar, nuclear) into usable
electrical energy.
Activity
Your Own Science Experiment
• Working together,
brainstorm what
question your group
would like to find
answers to.
• Choose from the
materials pictured.