Chapter_12 - ⎝ ⎛ = × = ∑ ∑ i i i i M M i i total (...

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Example: Door of width w and height h on hinges Ch 12: Static Equilibrium Focus: Translation and rotational equilibrium 0 i = i F 1) Total External Force = 0 0 i = i τ 2) Total External Torque = 0 Key ideas: Conditions for static equilibrium of an extended object: Can choose any origin – object is always at rest (no accel). Total torque = 0 about any point, if zero at one point, since total force is zero. Weight Where does the torque due to weight act? Write forces, then torques about chosen origin
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Ch 12: Static Equilibrium Key idea: r CG is where the weight acts Center of Gravity: r CG g r g r M M × = × = CM CM total τ M = total mass g g F M M i i = = weight Total Total weight force: g r g) r ×
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Unformatted text preview: ⎝ ⎛ = × = ∑ ∑ i i i i M M i i total ( Total torque from weight : 1 Example: At what point does a 1 kg mass balance a 1 kg ruler? Weight of ruler Object = many point masses M i located at r i with respect to chosen origin: CM CG r r = Torque from weight acts at CM weight Ch 12: Static Equilibrium g y M g y M U i i i CM weight Total = = ∑ Total Gravitational Potential Energy: M = total mass CM weight Total y g M U = y CM Torque due to Weight : M H W O Example: Door of width W and height H Should we find torque about O by t F r ⊥ F d or (d = moment arm) ?...
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This note was uploaded on 05/13/2010 for the course PHYSICS 53L taught by Professor Mueller during the Fall '07 term at Duke.

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Chapter_12 - ⎝ ⎛ = × = ∑ ∑ i i i i M M i i total (...

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