Potential Energy and Conservation of Energy

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Chapter 8 Potential Energy and Conservation of
Energy In this chapter we will introduce the
following concepts Potential energy
Conservative and non-conservative forces
Mechanical energy
Conservation
of mechanical energy The law of conservation of
energy will be used to solve a variety of
problems. As was done in Chapter 7, we use
scalars such as work, kinetic energy, and
mechanical energy rather than vectors. Therefore
the approach is mathematically simpler.
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Physics of Bungee-Jumping
One job of physics is to identify the different
types of energy in the world.
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8.2   Work and Potential Energy
Change in potential energy, ?U is defined as
being equal to the negative of the work done, W
on the object by the force.
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Conservative and Non-conservative Forces
A force is a conservative force if the net work
it does on a particle moving around any closed
path, from an initial point and then back to that
point, is zero. Equivalently, a force is
conservative if the net work it does on a
particle moving between two points does not
depend on the path taken by the particle. A
force is non-conservative if the net work it does
on a particle moving between two points does
depend on the path taken by the
particle. ExamplesConservative Forces
Gravitational force and Spring force.Non-conserv
ative Forces Kinetic frictional force and Drag
force.  
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8.4   Determining Potential Energy Values
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8.5 Conservation of Mechanical Energy
In an isolated system where only conservative
forces cause energy changes, the kinetic energy
and potential energy can change, but their sum,
the mechanical energy of the system, cannot
change.