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Unformatted text preview: W=(F)(s)cos φ W=F ⋅ s If φ is between 0 & 90: W is + If φ is between 90 & 180: W is – If φ = 90: W is 0 If total work is positive, speeds up If total work is negative, slows down If total work is 0, no change K = ½ mv 2 Work-Energy Theorem : W total = ∆ K K of particle is total W needed to accelerate it from rest to some speed and total work a particle can do in the process of being brought to rest W = ∫ F(dx) Spring: F = kx; k is spring constant W = ½ kx 2 P = ∆ W/ ∆ T = F(cos θ )v = F ⋅ v U grav = mgy W grav = - ∆ U grav K 1 + U 1 + W other = K 2 + U 2 (U = U grav ) U spring = ½ kx 2 If W other is positive, E increases If W other is negative, E decreases If W other is zero, mechanical E constant Conservative forces are… 1 Reversible 2 Expressed as the difference between initial & final values in a PE function 3 Independent of path 4 If start & end points the same, W=0 Law of Conservation of Energy ∆ K + ∆ U + ∆ U internal = 0 ∆ U internal = -W other Max points on U plot are...
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This note was uploaded on 10/06/2008 for the course MATH 216 taught by Professor Stenstones? during the Spring '07 term at University of Michigan.
- Spring '07