11/12/10 1 Physics 12111/12/10 2 Physics 121 F AB= F BA a =Fnetm11/12/10 3 Physics 121 FA B where F is either N, T, f, or WT = ks (spring)fA BμABNA BWE A= mAg11/12/10 4 Physics 121 tFnetnet=Inetp I= p = mv11/12/10 5 Physics 121 ()fBBfAAiBBiAABBAAvmvmvmvmvmvm+=+=+ 011/12/10 6 Physics 121 Definitions: Kinetic energy = Work done by a force F = Result 221mvxF xFmvnet= )(22111/12/10 7 Physics 121 F||FFssFsFsF ==cos Work ||11/12/10 8 Physics 121 F||FFsFsF ||sFsF = cosyyxxbababaabba+==cosIn general, for any two vectors that have an angle between them, the dot product is defined to be The dot product is a scalar. Its value does not depend on the coordinate system we select.11/12/10 9 Physics 121 F r = U11/12/10 10 Physics 121 mghUmghmvg==+ 0)(22111/12/10 11 Physics 121 (12mv2+12kx2) = 0Us=12kx211/12/10 12 Physics 12111/12/10 13 Physics 12111/12/10 14 Physics 121 (12mv2+ mgh +12kx2) = 012mvi2+ mghi+12kxi2=12mvf2+ mghf+12kxf2Mechanical11/12/10 15 Physics 12111/12/10 16 Physics 121 Power =Energy changetime to make the change=Wt= F net r t= F net v (for mechanical work)11/12/10 17 Physics 121 R Position Velocity Acceleration R R v t v v a t RvaRvvavtaRtv2 ===11/12/10 18 Physics 121 rRmvFrRvmFrRvamFanetnetnetˆˆ ˆ 222====always in order for the object to move in a circle with constant speed. Therefore, to do this, we need a net force.11/12/10 19 Physics 121 x y tt === degrees)(in 3602 radians)(in t=0 Uniform
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