Energy Conservation

We will encounter many situations or many systems for which the total energy remains constant. Energy may change from one form to another but the total energy -- the sum of potential energy plus kinetic energy -- will remain constant. We describe this by saying Energy is conserved.

E = PE + KE

E = constant

PE + KE = constant

E_i = E_f

PE _i + KE _i = PE _f + KE _f

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Examples:

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Pendulum

Energy changes form -- from PE to KE and from KE to PE -- but the total amount of energy,

E_Tot = KE + PE

remains constant,

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Free Fall

Energy changes form -- from PE to KE and from KE to PE -- but the total amount of energy,

E_Tot = KE + PE

remains constant,

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This is Energy Conservation.

Elastic Potential Energy			Nonconservative Forces
Return to ToC, Work and Energy

(c) 2002, Doug Davis; all rights reserved