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ERIC Number: EJ891970
Record Type: Journal
Publication Date: 2007-Feb
Pages: 5
Abstractor: As Provided
ISSN: ISSN-0031-921X
Energy and Change
Hecht, Eugene
Physics Teacher, v45 n2 p88-92 Feb 2007
When Feynman wrote, "It is important to realize that in physics today, we have no knowledge of what energy is," he was recognizing that although we have expressions for various forms of energy from kinetic to elastic, we seem to have no idea of what the all-encompassing notion of "energy" "is": This paper addresses that issue offering a definition of energy in terms of the more accessible concept of "change." The various forms of energy ("1/2mv[superscript 2]", "mgh", "1/2kx[superscript 2]", "qV", "mc[delta]T", "1/2I[omega][superscript 2]", "1/2CV[superscript 2]", etc.) are abstractions not directly observable. We see a cannonball rise in the air; we do not see potential energy ("PE"). We see physical change, not energy.
American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A