大学物理-保守力与非保守力省公开课金奖全国赛课一等奖微课获奖课件

一万有引力和弹性力作功特点(Thefeaturesoftheworkdonebytheuniversalgravitational&theelasticforce)

m’对m万有引力为m移动dr时,F作元功为1、万有引力作功(Workdonebyuniversalgravitationalforce)11/12m

从A到B过程中F作功：22/122、弹性力作功(Workdonebyelasticforce)弹性力x2x1xFOdxdW33/12保守力所作功仅决定于物体始、末位置,而与所经过路径无关．二保守力与非保守力保守力作功数学表示式(Theconservativeforce&Thenon-conservativeforceThemathematicalexpressionofworkbytheconservatiiveforce)

Theworkdonebytheconservatiiveforceonlydependsontheinitial&finalpositionsoftheobject&isindependentofthepaththatittook.1保守力作功特点(Thefeatureoftheworkdonebytheconservativeforce)

44/12质点沿任意闭合路径运动一周时,保守力对它所作功为零.非保守力:力所作功与路径相关(如摩擦力).WhenanobjectmovesaroundanarbitraryclosedlooptheworkdonebyconservativeforcesonitiszeroThenon-conservativeforce:Workdonebytheforcedependsonthepath(e.g

Thefrictionalforce)

2保守力作功数学表示式(Themathematicalexpressionofworkbytheconservativeforce)55/12三势能(Potentialenergy)与相互作用物体相对位置相关能量.Energydependsonoftherelativepositionoftheinteractiveobjects引力势能Gravitionalpotentialenergy引力功Workofgravitionalforce弹力功Workofelasticforce弹力势能Elasticpotentialenergy66/12物体在地球表面附近距地面高为y时,含有引力势能称为重力势能保守力对物体作功等于物体势能增量负值．保守力功(Workofconservativeforce)重力势能(Gravitypotenial)Theworkdonebytheconservativeforceonobjectisequaltothenegativevalueoftheincrementofthepotenialenergyofthatobject77/12在一维情况下作用于物体上在Ox轴上保守力,等于势能对坐标x导数负值。TheconservativeforceactingontheobjectalongtheOxaxisisequaltothenegativederivativeofpotenialenergywithrespecttothecoordinatex88/12势能是状态函数讨论Thepotenialenergyisafunctionofstate势能含有相对性,势能大小与势能零点选取相关,任意两点间势之能差却是绝正确.Therelativityofthepotenialenergy,thevalueofthepotenialenergydependsontheselectionofthezeropoint,thedifferenceofthepotentialenergybetweenanytwopointhasanabsolutemeaning99/12势能是属于物体系统.势能计算(Calculationofpotenialenergy)Thepotenialenergybelongtothesystemofobjects讨论1010/12

四势能曲线(Thepotenialenerycurve)重力势能曲线Curveofgravitypotenialenergy弹性势能曲线Curveofelasticpotenialenergy引力势能曲线Curveofgrav