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Unformatted text preview: Work of a Force : dU=F*ds*cos dU = F dr Work of a Variable Force U 1-2 = Fdr=F cosds Work Constant F along Straight Line U 1-2 = F c * cos (s 2-s 1 ) Work of a Weight : U 1-2 =-Wy Work of Spring Force : F=ks U 1-2 =-( *ks 2 ^2- *ks 1 ^2) Principle of Work & Energy T= *m*v^2 U 1-2 = -Wy+ *k(s 2 ^2-s 1 ^2) T1 + U 1-2 = T2 Work of Friction caused by Sliding mv1^2 + P*s k*N*s = mv2^2 mv1^2 k*N*s = mv2^2 (No P) mv^2 k*m*g=0 Power & Efficiency P = dU/dt = Fdr/dt = Fv P=T*v P=F*v cos =output/input (applies to both power & energy) Conservative Forces & PE V(g)=Wy V(g)>0 if y is above the datum V(g)<0 is y is below the datum Elastic PE V(e)= ks^2 V(potential function) =V(g)+V(e) Conservation of Energy T1 + V1 = T2 + V2 = constant Linear Momentum & Impulse L = mv I = Fdt = F(t2-t1) Principle of Linear Impulse & Momentum mv1 + Fdt = mv2 mvx1 + Fxdt = mvx2, same for y&z PLIM for System of Particles mi(vi)1 + Fi*dt = mi(vi)2...
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- Spring '08