Download Energy Conversions and Conservation

Energy Conversions and
Conservation
CHAPTER 9 SECTIONS 2-3
Types of Heat Transfer
 Convection – transfer of
thermal energy by the movement
of a liquid or gas
 Conduction - Particles from a
warmer object transfer by
colliding with particles from
the cooler object.
 Radiation - Thermal energy
transferred through
electromagnetic waves
 Visible light, ultraviolet,
infrared, x-rays…..
You Try! Convection, Conduction, or Radiation?
1. Your feet get burned when crossing
hot pavement barefoot
2. You feel heat from the iron without
touching it
3. Your face tingles and feels warm when
sitting out in the sun
4. When the heater is running, your
room on the second floor feels warmer
than downstairs.
What are energy conversions?
 A change from one form of energy to another.
Chemical/Potential energy in
food is converted into kinetic
energy when you are active
AND thermal energy to
maintain your body
temperature.
Potential energy of the skater
is converted into kinetic
energy as he moves down the
half-pipe.
Energy Conversions in a hair dryer
Energy Conservation in Plants
 Photosynthesis uses energy from the SUN to make
new substances that have chemical energy…light
energy is changed into chemical energy…
 Light energy comes from the sun
plants change it
into chemical energy
you body changes it into
another chemical energy when you eat it
your
body changes it to kinetic energy to function
Law of Conservation of Energy
 Energy cannot be CREATED or DESTROYED! It is
just converted into other forms of energy.
 Where does the Energy go??
1. Friction: force that
opposes motion
between two
touching objects
2. Some energy is
transferred into
thermal energy
Remember the bouncing ball lab??
 When you dropped the ball, its bounce height was
lower than the original drop height. WHY???
ANSWER…
 The potential energy at the top was converted to
kinetic energy as it dropped. When the ball hit the
floor, some of the energy was released as FRICTION
and thermal energy from
the friction! Some energy also
changed into sound energy!
Therefore, it didn’t have
enough energy to bounce
back to its original height.