Chapter 7 Notes

Chapter 7 Notes - Chapter 7 Notes Energy o Every physical...

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- Energy o Every physical process that occurs in the Universe involves energy and energy transfers or transformations o The energy approach to describing motion is particularly useful when the force is not constant o An approach will involve Conservation of Energy - Work o The work, W , done on a system by an agent exerting a constant force on the system is the product of the magnitude, F , of the force, the magnitude d of the displacement and cosθ , where θ is the angle between the force and the displacement vectors = ∥ = = W F d Fcosθd Fd cosθ o Work II = W Fdcosθ d starts when the force is applied, stops when the force is taken away No work is done if the force does not move the object through a displacement o d = 0 No work is done if the force applied is perpendicular to the displacement o °= cos90 0 o Work—Positive, Negative, or Zero Work is positive when lifting the box Work would be negative if lowering the box Work would be zero if he walks with the box o Work III The sign of the work depends on the direction of F relative to d Positive o F and d in the same directions < ° θ 90 Negative o F and d in opposite directions ° < ° 90 θ 180 SI Units
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This note was uploaded on 04/17/2008 for the course PHYS 31 taught by Professor Dishaw during the Winter '08 term at Santa Clara.

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Chapter 7 Notes - Chapter 7 Notes Energy o Every physical...

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