大學(xué)物理-保守力與非保守力

1、一 萬有引力和彈性力作功的特點(diǎn) (The features of the work done by the universal gravitational & the elastic force) m對(duì)m的萬有引力為m移動(dòng)drF作元功為 1、萬有引力作功 (Work done by universal gravitational force)1m 從 A 到 B 的過程中F作功： 22、彈性力作功 (Work done by elastic force)彈性力x2x1xFOdxdW3保守力所作的功僅決定于物體始、末位置,而與所經(jīng)過的路徑無關(guān)二 保守力與非保守力 保守力作功的數(shù)學(xué)表達(dá)式(The

2、conservative force & The non-conservative force The mathematical expression of work by the conservatiive force) The work done by the conservatiive force only depends on the initial & final positions of the object & is independent of the path that it took.1 保守力作功的特點(diǎn) (The feature of the work done by t

3、he conservative force) 4質(zhì)點(diǎn)沿任意閉合路徑運(yùn)動(dòng)一周時(shí),保守力對(duì)它所作的功為零.非保守力:力所作的功與路徑有關(guān)(如摩擦力) .When an object moves around an arbitrary closed loop the work done by conservative forces on it is zeroThe non-conservative force:Work done by the force depends on the path(e.g The frictional force) 2 保守力作功的數(shù)學(xué)表達(dá)式 (The mathemat

4、ical expression of work by the conservative force)5三勢能 (Potential energy)與相互作用的物體相對(duì)位置有關(guān)的能量.Energy depends on of the relative position of the interactive objects引力勢能 Gravitional potential energy引力的功 Work of gravitional force彈力的功 Work of elastic force彈力勢能 Elastic potential energy6物體在地球表面附近距地面高為y時(shí),具有的引

5、力勢能稱為重力勢能保守力對(duì)物體作的功等于物體勢能增量的負(fù)值保守力的功(Work of conservative force)重力勢能(Gravity potenial)The work done by the conservative force on object is equal to the negative value of the increment of the potenial energy of that object7在一維情況下作用于物體上的在Ox軸上的保守力,等于勢能對(duì)坐標(biāo)x的導(dǎo)數(shù)的負(fù)值。The conservative force acting on the objec

6、t along the Ox axis is equal to the negative derivative of potenial energy with respect to the coordinate x8 勢能是狀態(tài)的函數(shù)討論The potenial energy is a function of state 勢能具有相對(duì)性,勢能大小與勢能零點(diǎn)的選 取有關(guān),任意兩點(diǎn)間的勢之能差卻是絕對(duì)的.The relativity of the potenial energy, the value of the potenial energy depends on the selection o

7、f the zero point,the difference of the potential energy between any two point has an absolute meaning9 勢能是屬于物體系統(tǒng)的. 勢能計(jì)算(Calculation of potenial energy )The potenial energy belong to the system of objects討論10 四勢能曲線(The potenial enery curve)重力勢能曲線Curve of gravity potenial energy彈性勢能曲線Curve of elastic potenial energy引力勢能曲線Curve of