Download PE and KE

What is Energy?
Energy
• The ability to do work or cause change.
Potential & Kinetic
Energy
Potential Energy
Potential Energy
• Stored energy.
• Energy of position.
• The amount of usable energy in a body at
rest.
• Also called gravitational potential energy.
Potential Energy
• Even though an object is not moving, it
has the ability to move, if in the right
position.
• Anything that can fall has the ability to
create change.
Examples of
Potential Energy
• By stretching a rubber band, you give it
potential energy.
• A vase on a shelf has stored potential
energy.
• A football being held by a quarterback
has potential energy until it is thrown
and it turns into kinetic energy.
Potential Energy depends on
Mass and Height …
• …So, potential energy can be increased by:
– Increasing Height
– Increasing Mass
Kinetic Energy
Kinetic Energy
• Energy of matter in motion.
• Measured by how much work is done to put
an object in motion or to rest.
• The faster the object moves, the more kinetic
energy.
Kinetic Energy depends on
Mass and Speed …
• …So, kinetic energy can be increased by:
– Increasing mass
– Increasing speed
Examples of
Kinetic Energy
• A basketball player has kinetic energy.
The movements that he/she does show
the energy that is being displayed while
he/she is moving.
• When you are running, walking,
jumping, or skiing, your body is
exhibiting kinetic energy.
• Even molecules of water in a glass have
kinetic energy.
Both Potential and
Kinetic Energy
• A waterfall has both
kinetic and potential
energy.
• The water at the top of the
waterfall has stored
potential energy.
• Once the water leaves the
top of the waterfall, the
potential energy is
changed into kinetic
energy.
Conservation of
Energy
Law of Conservation
of Energy
• Energy cannot be created or destroyed;
it can only be changed from one of form
of energy to another form.
• The amount of energy stays the same.
• The ball starts with 100
J of potential energy.
As the ball falls toward
the ground, it gains its
kinetic energy at the
expense of its potential
energy, so these two
quantities always add
up to 100 J.
• What is the potential
energy and kinetic
energy of the ball at the
¾ mark?
• When an object begins to move, the
potential is transferred to kinetic energy.
• Ex: pendulum, roller coaster, skier,
falling objects.
• Total ME (Mechanical Energy) = PE + KE
Kinetic vs. Potential
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