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

Ei = Ef

PE i + KE i = PE f + KE f


Examples:
Pendulum

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

ETot = KE + PE

remains constant,







Free Fall

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

ETot = KE + PE

remains constant,





This is Energy Conservation.

Elastic Potential Energy

Nonconservative Forces
Return to ToC, Work and Energy
(c) 2002, Doug Davis; all rights reserved