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Potential Energy. The energy due to an object’s position or location. M. W= mgy. = PE g. y. M. For PE, choose a “zero-level” (reference level). Floor Desk Earth Etc. The work done by gravity: W g = - mgy. W g = - Δ PE= mgy i - mgy f. M. y. M. EXAMPLE.
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Potential Energy • The energy due to an object’s position or location. M W=mgy =PEg y M
For PE, choose a “zero-level” (reference level). • Floor • Desk • Earth • Etc.
The work done by gravity: Wg = -mgy Wg = -ΔPE=mgyi- mgyf M y M
EXAMPLE • An 86.0kg refrigerator is hauled up a ramp that is 20.0m long and 5.50m high. Find • Its potential energy relative to the bottom of the ramp. • The work done by gravity.
Path Independence • Gravity is path independent: the work done by gravity depends on the object’s displacement, not how it got there. • HW: Read pp. 127-130 • Do 19-29