phys111_sep23_lecture.pdf

# phys111_sep23_lecture.pdf - Conservative Non-Conservative...

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• Yousef95
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Conservative & Non-Conservative Forces Work and energy can be recovered Energy-dissipative; work done cannot easily be recovered Work independent of path ; depends only upon the initial and final positions Will have a potential energy function associated with it Gravity, Spring force, Electromagnetic forces Kinetic friction, air drag, propulsive forces Work depends on path

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Non-conservative force: friction The blue path is shorter than the red path The work required is less on the blue path than on the red path Friction depends on the path and so is a non- conservative force
Work-Energy Theorem The theorem can be expressed in terms of the work done by both conservative forces, W c , and nonconservative forces, W nc W c + W nc = Δ KE Potential Energy associated with the position of the object within some system a property of the system , not the object collection of objects interacting via forces

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For every conservative force: a potential energy function PE exists Evaluating the difference of the PE function at any two points in an object’s path gives the negative of the work done by the force between those two points Work-Energy Theorem PE = mgy, for falling objects
Clicker Question 6.6 Two blocks are connected as shown. The rope and pulley are of negligible mass. When released, the block of mass m 1 slides down the ramp and the block of mass m 2 moves upward.

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