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Energy
Question
• What does it mean when we say “that kid
has a lot of energy?”
•It means that kid is
“Active” and moving.
•How does that relate to
work?
Energy
• How can you tell if someone has a lot of
energy?
• How does that relate to work?
Work = Energy
• Work
– Moving an object by pushing it.
– a transference of energy
• Energy:
– The Ability to do work (move both large or small objects)
– It’s what causes change.
Force & Work
Force  mass  acceleration
Work  Force  Distance
[kg m]
N
2
[s ]
2
[kg m ]
J
2
[s ]
Work = Energy
Work  Force  Distance
Energy  Force  Distance
2
[kg m ]

J
2
[s ]
2
[kg m ]

J
2
[s ]
Notice that the formula’s for both work and energy are exactly the
same with the exact same unit (J – Joules)
Two Types of Energy
• Potential – Stored Energy (NOT in motion)
– Depends on the objects position or shape
• Kinetic – Energy in motion
– Depends on mass & velocity of an object
6 Forms of Energy
– Gravitational
– Elastic (Spring)
– Sound (Oscillation of air molecules)
Heat (Kinetic Energy of Whole Motions of Atoms)
Light (Photon Oscillations of Electric and Magnetic Fields)
Chemical (Potential Energy in the Bonds between Atoms)
Electrical (Kinetic Energy of Electrons found in Atoms)
Nuclear (Potential Energy in the Bonds of Protons in the Nucleus)
Atomic Sized Objects
•
•
•
•
•
Large Objects
• Mechanical (Physical Moving Objects)
Mechanical Energy
• Moving large objects.
Three Forms of Mechanical Energy
• Gravitational
• Elastic
• Sound
Mechanical Energy
Kinetic
Energy
KE=1/2mv2
(work = Force x Distance)
Potential
Energy
PE=mgh
Work = Weight x Height
• Gravitational Energy: Gravity making the
object move.
Mechanical Energy
• Elastic Energy: movement caused by
bending or distorting.
EKE = ½ mv2
EPE = kd2
Work = Force x Distance
Mechanical Energy
• Sound = Movement of air back and forth
as the wave goes through.
Work = Force x Distance
Energy Due to Motion of
Atomic sized particles
Heat / Thermal Energy
= Heat Energy: (Thermal) Movement of the
Whole atom. (average kinetic energy)
Heat Energy is the form of energy that
is related to the motion of atoms
Measurement of total movement
of molecules (Kinetic Energy)
Heat energy is measured
by “Temperature”
So a higher temperature simply
means that the atoms are hitting
the thermometer fast & more often
Liquid A
Liquid B
Think: Which of the two liquid samples
has a higher temperature? WHY?
A higher temp. means more Kinetic
Energy for the molecules!
Work = Force x Distance
Heat / Thermal Energy
• Heat or Thermal Energy: is the kind of
energy that is related to and/or caused by fast
moving particles that make up the material.
Though lava
moves fairly
slow, the
particles are
moving very
fast.
Light
• Electromagnetic (AKA – Light):
– Movement of charged particles which induce WAVES
of Electromagnetic radiation – AKA photons of Light!
Light
Energy from the motion of a moving charged particle in the atoms disturbs the
electromagnetic fields which effects other charged particles in other atoms.
Electromagnetic Fields
Radiation
+/-
Work = Force x Distance
+/-
Light Spectrum
Examples
Chemical
• Energy stored in the bonds between the
atoms.
C
Demo: hold hands & snap release
C
Work = Force x Distance
Chemical
Work = Force x Distance
Electric Energy:
Work = Force x Distance
Electrical Energy: Motion (flow) of Electrons
These charges can be made
to move through a wire
Electric energy “flows” through
wires to our houses where
we plug stuff in!
Electricity is electric energy
Lightning is Electric energy
Other Examples of Electric Energy
Electrical Energy
• Comes from the movement (or flow) of
Electrons from the atom
Electrons from the outer
edges of the Atom
Work = Force x Distance
NuclearComes
Energy
from the Stored Energy from the
Nucleus of the atom
• Energy stored in the bonds of protons in
the nucleus.
Nucleus of the
Atom:
Protons & Neutrons
Work = Force x Distance
Nuclear Energy - Fission
Demo: Break hands apart – point out the
release of energy from the break
Work = Force x Distance
Nuclear Energy - Fusion
• AKA Solar Energy
Demo: Clap – point out the release of
energy from the collision
Work = Force x Distance
Acronym
• Original List
– Moving Large Stuff
• Mechanical
– Grav, elast, sound
– Moving Atomic Stuff
•
•
•
•
•
Heat
Light
Chemical
Electrical
Nuclear
• MECH-’n Legs
–
–
–
–
–
–
–
–
–
Mechanical
Electrical
Chemical
Heat
Nuclear
Light
elastic
gravitational
sound
I will wait for the sumo industrial strength walker
Energy
Defined
Example
Mechanical
Any Large Object Moving –
Forwards/Backwards/Up/Circle
Car, Generator, ball, fan,
blender, motor
Electrical
Any shock, zap, lightning’ish
phenomenon
Outlet, Battery, Lightning
Chemical
Any chemical reaction, fuel or
explosion.
Gas, food, sugar, fire
Heat
Anything that’s hot/cold
CCR
Light bulb, fire etc.
The sun
Nuclear
Light
Duh. Any form of radiation.
ROY G. BIV, radio, mw,
IR, VL, UV, XR, Gma
Elastic
Any bending, twisting or
stretching of an object.
Bending Ruler, stretching
a rubber band.
Gravitational
Any falling object.
Pendulum, falling ball.
Sound
Any noise.
Rock concert.