• ENERGY: the
_________________________________
_________________________________
• When you do work on an object, you
___________________ energy to that object.
• Whenever work is done, energy is
__________________________________ or
__________________________________ to
another system.
• Energy is also measured in ______________
• Energy is not a substance!
• Energy has no direction!
Energy Systems
• Scientist study energy
___________________________.
• Boundaries define a system and are
set by the observer.
• Systems may be
____________________________
• CLOSED SYSTEM: the flow of energy
into and out of a system is small
enough that it can be ignored
• OPEN SYSTEM: the system
exchanges energy with the space that
surrounds it.
• KINETIC ENERGY (KE or EK): Energy of a
_________________________________due
to the object’s motion.
• Kinetic energy depends on…
– ____________: more mass = more EK
– ________________: faster = more EK
• Kinetic Energy Equation
Kinetic Energy = ½ x mass x speed squared
EK = ½mv2
• POTENTIAL ENERGY: Energy that an
object has because of the
_________________________________
_________________________________
• Potential energy is
_________________________________
• There are many types of potential
energy that we will cover…
•
•
•
•
•
Gravitational
Elastic
Chemical
Electrical
Magnetic
• Potential Energy + Kinetic Energy =
_________________________________
• GRAVITATIONAL POTENTIAL ENERGY (GPE or EG):
Energy an object has due to its relative height
• Gravitational potential energy (EG) depends on:
– ____________________: more mass = more EG
– ____________________: higher = more EG
– Gravitational free-fall ______________________: 9.81m/s2
(same everywhere on Earth)
• Gravitational Potential Energy Equation
GPE = mass (m) x free-fall acceleration (g) x height (h)
EG = _________________
• LAW OF CONSERVATION OF ENERGY: States that energy
cannot be _______________________________ or
________________________________
• Energy doesn’t appear out of nowhere.
• Whenever the total energy in a system increases, it must be due to
energy that enters the system from an external source.
• Energy is __________________________ to another type
or _______________________ to another system/object.
– Energy doesn’t disappear, but it can be changed to another form.
Energy Transfers and Transformations
• Energy readily ______________ from one form to another.
A)
7kg
5m
12kg
B)
C)
7kg
5m
3m
D)
E)
7kg
5m
Example:
GPE & KE
7kg
5m
Energy Transfers and Transformations
• Which one of the spheres has the most
gravitational potential energy?
• Which one of the spheres has the most
kinetic energy?
• What is the gravitational potential energy of
the system in A?
• What is the kinetic energy of the system in
D?
• Which sphere has kinetic and gravitational
potential energy present?
• Let the mass of the skier be 50kg and g= 10m/s2
• Kinetic Energy (KE)
• Gravitational Potential Energy (PE)
• Kinetic Energy + Potential Energy = (Total) Mechanical Energy
Types of Energy
• 2 Main Energies we focus on:
– _________________________________
– Gravitational Potential Energy (GPE)
• Other types of potential energy we study:
– Elastic Potential
– _________________________________
– Electrical Potential
– _________________________________
• Other types of nonmechanical energy we
study:
– _________________________________
– Thermal
– Sound
– _________________________________
Mechanical
Energy at a
larger level
• ELASTIC POTENTIAL: Energy stored in any
type of ______________________________
or __________________________________
material
– Such as a spring or a rubber band.
• CHEMICAL POTENTIAL: Energy stored due
to the relative __________________________
of the atoms a substance contains and the
_____________________________________
between the atoms.
–
–
–
–
Fossil fuels
Batteries
Food
Chemical Reactions
• ELECTRICAL POTENIAL
• Electricity is derived from the flow of
_______________________________________(electrons
)
• Electric current running through appliances
• Electrostatic energy comes from a separation of
_______________________________________________
• Lightning bolt
• MAGNETIC POTENTIAL: Energy derived from the
_______________________________________ of materials.
Electromagnetic
Energy
Flow of electrons
(electricity) from a battery
to a light bulb
• ELECTROMAGNETIC (LIGHT): Energy in the form of
_________________ that includes radio waves, microwaves,
infrared waves, visible light, ultraviolet rays, x-rays, and
gamma rays.
– Only energy that can travel through a vacuum (empty space)
– Living things ultimately get energy from the Sun.
• Plants use photosynthesis to turn the energy in sunlight into
________________________________________________
• SOUND ENERGY
• NUCLEAR (2 TYPES)
• NUCLEAR FUSION: _______________________________________
• Process in Sun and other stars
• Can’t be used in power plants yet – too hard to control
• NO radioactive waste
• NUCLEAR FISSION: _______________________________________
• Process in nuclear power plants and submarines
• Creates radioactive waste
• THERMAL: The kinetic energy of
_________________________________________________
vibrating is related to heat and temperature.
• Lots of systems lose energy in the form of thermal energy
More thermal energy = hotter = atoms move faster
Less thermal energy = cooler = atoms move slower