1/31/11 1 Physics 1221/31/11 2 Physics 1221/31/11 3 Physics 1221/31/11 4 Physics 122 lkT =1/31/11 5 Physics 1221/31/11 7 Physics 122 x x x x vaFxnet 0 0 0 0 0 0 0 01/31/11 8 Physics 122 FS MFE MWhat happens to these forces when the mass is at equilibrium (at rest)? when the mass is above or below equilibrium (possibly moving)?1/31/11 Physics 122 91/31/11 10 Physics 122 Air track Cart Sonic ranger1/31/11 11 Physics 122 x N tc W ec T sc 01/31/11 12 Physics 122 xmkmkxmFanet ===[]22T1ML1TMLM/=== xFmk1/31/11 13 Physics 122 T sm W em T = klAt equilibrium: (y = 0) kl0= mgNon-equilibrium: (y > 0) Fnet= k(l0 y) mg= kl0 ky mg= ky1/31/11 14 Physics 122 vdtdxxdtdv==20mk201/31/11 15 Physics 122 fdtdggdtdf==1/31/11 16 Physics 122 tx cos=tAvtAx000sincos==1/31/11 17 Physics 122 TTTtt220:20:000== 1/31/11 18 Physics 122 x t t 0 x(t) = Acos(0t)x(t) = Acos(0(t t0))x(t) = Acos( 0(t t0))= Acos( 0t 0t0) = Acos( 0t
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