Download Energy Conservation - Science with Ms. C

Energy Conservation
6.P.3A.2
Law of Conservation of Energy
• The Law of Conservation of Energy states that energy cannot
be created nor destroyed.
• Energy can be transformed from one form into another, but
the total amount of energy never changes.
Mechanical Energy Transformations
• When water is behind a dam, it has potential energy.
• The potential energy of the water changes to kinetic energy in
the movement of the water as it flows over the dam.
Mechanical Energy Transformations
• When a rubber band is stretched, kinetic energy is
transformed into potential energy.
• The further back you stretch the rubber band, the greater
potential energy, and the more energy that will be transferred
as kinetic energy.
• When a stretched rubber band is released its potential energy
is transformed into kinetic energy as the rubber band moves.
Mechanical Energy Transformations
• When a book is lifted to a shelf, kinetic energy is transformed
into potential energy.
• If the book falls off the shelf the potential energy is
transformed to kinetic energy.
Conserved Energy
• Energy is conserved during energy transformations:
• Transformations may occur between any of the various types of
energy but energy itself is never lost.
• The potential energy that a book on a shelf has is from the kinetic
energy it took to lift the book to the shelf.
Pendulum
• A swing pendulum (such as a Newton’s cradle)
also demonstrates how energy is conserved as it
changes forms.
• Kinetic energy is used to pull a ball back; this
energy is transformed into potential energy.
• The ball is released and the ball swings back
toward the other three balls (kinetic energy).
• The moving ball strikes the stationary ball and the
kinetic energy is transferred from one ball to the
next.
• The last ball swings away from the others because
of the kinetic energy that was transferred to the
ball.
• If this experiment is repeated by pulling back two
balls, then two balls will swing off of the other end.
• This shows conservation of energy because one
ball has enough potential energy to cause one ball
to move; two balls cause two to moves, and so on.
Transformations
• Although energy is not lost during energy transformations,
some is transformed into heat and friction.
• This means that all of the potential energy stored in a book is
not going to be transformed into kinetic energy.