Download What is energy?

Starter
Directions: Draw the following table.
Match the example up with the
correct simple machine type:
Wedge, Lever, Wheel and Axle`,
Pulley
Example
Type
1. Shovel
2. Axe
3. Doorknob
4. Window blinds
Energy
Day 30
Essential Questions
• What is energy?
• How is energy stored? (give
examples).
• Compare & contrast the energy of a
book sitting high on a shelf with a
book falling to the ground.
Energy Reading Passage
• Please read passage in its entirety.
• Answer the analysis questions about
the passage.
• What is matter and energy?
What is Energy
• Energy is the ability to do work.
• In other words, energy is transferred
by a force moving an object through
a distance.
• Work and energy are closely related.
• Work is a transfer of energy
• Work and energy are measured
joules (J).
• Energy may take several forms!
Energy forms
• Energy forms can be classified as
either
– Kinetic energy
– Potential energy
• Forms
–
–
–
–
–
–
–
–
Gravitational potential energy
Elastic potential energy
Mechanical energy
Thermal energy
Chemical energy
Electrical energy
Electromagnetic energy (light)
Nuclear energy
Kinetic Energy
• Kinetic energy is the energy of
motion.
• An object that has motion - whether
it is vertical or horizontal motion has kinetic energy.
• There are many forms of kinetic
energy
– KE = 0.5 • m • v2
– where m = mass of object
– v = speed of object
Potential Energy
• An object can store energy as the
result of its position.
• For example, the heavy ball of a
demolition machine is storing
energy when it is held at an elevated
position.
• This stored energy of position is
referred to as potential energy.
• Potential energy is the stored energy
of position possessed by an object.
Gravitational Potential Energy
• Gravitational potential energy is the
energy stored in an object as the
result of its vertical position or
height.
• The energy is stored as the result of
the gravitational attraction of the
Earth for the object.
Kinetic vs. Potential
Kinetic energy
• Motion
• The closer the object is
to the ground the
greater the kinetic
energy.
•
KE=1/2(m)v2
KE= kinetic
m= mass
v= velocity
Unit=Joule
Potential Energy
• Stored (Has the
potential to move)
• The higher the object
the greater the potential
energy.
• PE=m(g)(h)
PE=Potential
m= mass
g= gravity
h= height
Unit=Joule
Explain: Gravitational Potential Energy
Write the following information.
Formula:
PEg= mgh
PEg= FWh
Variable
PEg– gravitational potential energy
m – mass
h – height
FW – weight
g-gravity
Units
J
kg
m
N
m/s2
Explain: Gravitational Potential Energy
Write the following information.
PEg= mgh
PEg= FWh
PEg
PEg
m
g
h
FW
h
Explain: Kinetic Energy
Write the following information.
Kinetic Energy is energy of motion.
Formula:
KE=½ mv²
Variable
Units
KE – kinetic energy
J
m – mass
kg
v – velocity
m/s
Explain: Kinetic Energy
On the back of the index card, write the following information.
KE=½ mv²
KE
½
m
v
v
The ball starts at rest waiting (PE) to move. Then with a
force it moves down the hill (KE).
If an object has PE it will have KE.
You cannot have one without the
other.
KE and PE
http://www.teachersdomain.org/resou
rce/hew06.sci.phys.maf.rollercoaster/
Forms
• Elastic potential energy
– The energy stored in elastic materials as the result of their
stretching or compressing
• Mechanical energy
– The energy acquired by the objects upon which work is done
• Thermal energy
– The energy a substance or system has related to its temperature
(vibrating or moving molecules)
• Chemical energy
– The energy stored in the bonds of chemical compounds (atoms
and molecules)
• Electrical energy
– The energy carried by moving electrons in an electric conductor
• Electromagnetic energy (light)
– The energy that is reflected or emitted from objects in the form of
electrical and magnetic waves that can travel through all space
• Nuclear energy
– The energy released when the nuclei of atoms are split or fused.
Examples of each form
• Gravitational potential energy
– the heavy ball of a demolition machine when it is held at
an elevated position
• Elastic potential energy
– rubber bands, bungee chords, trampolines, springs
• Mechanical energy
– Moving car, every moving object
• Thermal energy
– Fire
• Chemical energy
– Fuel
• Electrical energy
– circuits
• Electromagnetic energy (light)
– Sun, stars
• Nuclear energy
– Radiation therapy
Energy
• All forms of energy are related
• Each form can be converted or
changed into the other forms.
Explore: Energy Forms
• Directions: Draw a table with 6
columns. Label the columns as
mechanical energy, thermal energy,
chemical energy, electrical energy,
electromagnetic energy, and nuclear
energy.
• Directions: Classify the following
scenarios under the correct energy.
Explore: Energy Forms
•
•
•
•
•
•
•
•
•
speeding train
gasoline
ultra-violet
flashlight
oven
bouncing ball
KE+PE
fusion/fission
chemical bonds
•
•
•
•
•
•
•
•
moving electrons
heat
ball rolling
Digestion
sun
Atomic Bomb
radio waves
Ice Boiling Water
What Energy Form?
• Directions: Label the picture with the
correct energy form. Electrical,
nuclear, Thermal, and Mechanical
a.
b.
c.
d.
Exit Slip
Directions: Copy the examples and label
which one is KE or PE.
1. a moving skateboard
2. a dry cell of a battery
3. a rock at the edge of a cliff
4. an acorn hanging from an oak tree
5. a glass of milk
6. a person climbing a ladder
7. Gasoline
8. a piece of celery
9. a basketball passing through a hoop
10. blowing wind