Download 3.1 Notes Energy: the ability to do work or to cause change. Kinetic

3.1 Notes
Energy: the ability to do work or to cause change.
Kinetic Energy: energy of motion. A moving object has
the most kinetic energy at the point where it moves the
fastest.
Kinetic energy of an object depends on both its mass and
velocity.
● As mass increases, kinetic energy increases.
● As velocity increases, kinetic energy increases.
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Potential Energy: stored energy
● Gravitational Potential Energy – Potential energy
that depends on height.
Examples: lab activity of tennis ball falling,
pendulum swinging
Formula:
● Elastic Potential Energy – Potential energy
associated with objects that can be stretched or
compressed
Examples: rubber band, slinky, bow
● Chemical Potential Energy – Potential energy
associated with the chemical composition of an
object. The energy is stored in the chemical bonds.
Examples: food, wood before it burns, fossil
fuels
Some of the Different Forms of Energy
FORMS OF ENERGY:
Mechanical Energy- energy that moves objects
Examples: Moving a coffee mug, Turn a car key
Sound Energy- results from the vibrations of particles in matter.
Sound travels when gas molecules vibrate.
Examples: Moving a coffee mug, Turn a car key
In a vacuum there is no sound (no air molecules
to vibrate!
Chemical Energy- Energy that is stored in matter.
Examples: Energy is stored in your cells, in food
Thermal Energy- measures the amount of motion in the
particles of matter
Examples: Atoms and molecules constantly moving
Electromagnetic Energy- energy transmitted through space,
can be transferred through empty space.
Examples: Visible light, X-rays, Microwaves
Nuclear Energy: an atoms nucleus breaks apart, or when two
nuclei join together energy is released.
Examples: The Sun
Electrical Energy: moving electric charges produce this energy
Examples: power from batteries, wires etc.
Section 3.2 Energy can Change Forms but is Never Lost
CONVERSIONS BETWEEN KINETIC AND POTENTIAL
ENERGY:
Skier:
What would happen if you get a more massive skier from the
same height?
● The more massive skier would have more GPE, therefore more would
convert to KE
Describe the Ratio of KE and PE at the top, middle, and bottom
of the hill.
TOP:
100% GPE (Max)
MIDDLE:
BOTTOM: 0 % GPE
Waterfall
0 % KE
50/50
100 % KE (Max)
Describe the Ratio of KE and PE at the top, middle, and bottom
of the waterfall.
TOP:
100% GPE (Max)
MIDDLE:
BOTTOM:
0 % KE
50/50
0 % GPE
100 % KE (Max)
Roller Coaster:
How does the GPE at the same height compare when a roller
coaster car is full and empty. How does this affect the KE?
● At the same height, the car full with people will have more GPE,
because of an increase in mass. Therefore there will be more GPE
converted to KE.
Describe the Ratio of KE and PE at the top, middle, and bottom
of the hill.
TOP:
100% GPE (Max)
MIDDLE:
0 % KE
50/50
BOTTOM: 0 % GPE
100 % KE (Max)
Pendulum:
Where is the greatest amount of KE, why?
● The greatest amount of KE is at the bottom because all of the GPE converted
to KE
Where is the greatest amount of GPE? Why?
● At each end, because the pendulum is at it’s highest height, and not in
motion.
Describe the Ratio of KE and PE at the ends and bottom of the
curve
● TOP ENDS:
100% GPE (Max)
0 % KE
● BOTTOM:
0 % GPE
100 % KE (Max)
ENERGY CHANGES FORMS:
Know all the forms of energy: Chemical, Mechanical, Sound,
Mechanical, Electrical, Thermal, Electromagnetic, and Nuclear
Plant’s Nutrition: Electromagnetic to chemical energy
Candy Bar: Chemical to Mechanical
Toaster: Electrical to Thermal
Microwave: Electric to Electromagnetic
Waterfall/Electrical Generators: Mechanical to Electrical
Battery powered Remote Control: Chemical to Electrical
Radio: Electrical to Sound
Human Body: Chemical to Mechanical
Light Bulb: Electrical to Thermal/Electromagnetic
LED Lights: Electrical to Electromagnetic
Ignite a Match: Chemical to Thermal/Electromagnetic
Windmills: Mechanical to Electrical
Solar Panels: Electromagnetic to Electric
Which is more efficient? LED or Regular Light Bulbs
● LED, they convert more electric energy to electromagnetic,
rather than waste it on thermal
Law of Conservation of Energy:
● Energy can’t be created or destroyed, it can only be transferred into other
forms!
o Read the diagram on pg. 81!
● The more energy efficient something is, the more is converted to what you
need it to do!
o Fan Example pg. 83
Energy Conversions and Fossil Fuels
Background information:
1. The sun is the major source of energy for
most of Earth’s processes.
2. On the sun, hydrogen atoms join or fuse to
form helium. This is called nuclear fusion. It
gives off electromagnetic energy.
3. Some of this energy reaches Earth.
4. Photosynthesis then begins on Earth.
Plants grow, animals eat the plants…
5. When plants and animals die, dirt
(sediment) slowly covers these. The energy in
them is now stored and trapped within them.
6. The resulting pressure along with high
temperatures turns the animal and plant
remains into coal.
Fossil Fuels
1. Fossil Fuels: Coal, petroleum, and
natural gas are all known as fossil fuels.
2. A fuel is a material that stores chemical
potential energy.
3. Law of Conservation of Energy: Energy is
not created or destroyed. It changes forms.
The energy for fossil fuels ultimately comes
from the sun.
4. Fossil fuels can be burned to release the
chemical potential energy. (steam and heat
turn tubines to produce electricity)
5. Burning fossil fuels is a process known
as combustion.
PROBLEM: fossil fuels are non-renewable
resources. They take millions of years to
form.