※ 引述《zjps3407 (阿銘)》之銘言： : 標題: [問題] 2題有關能量的題目 : 時間: Sat Nov 6 16:00:40 2010 : : → ^ ^ ^ : (a)[5%]Is the force field F(x,y,z) = -yi +xj +2k conservative? Why? [Hint] Consider the work done on moving a point particle along the unit circle centered at the origin in the xy plane. [Hint2] Ask yourself that what does mean a "conservative" force field. [Hint3] Just calculate the work you done on moving a point particle along the unit circle. Just try, OK? If you get a non-zero result, what does that mean? : (b)[5%]For a conserved force field : → → : F(x,y,z) with potential energy U(x,y,z), show that F is perpendicular to the : equipotential surface U(x,y,z) = constant. [Hint] In (a), what is the work you done on the particle → if you move the particle along the direction perpendicular to F ? Did you change the potential energy of the particle? : a小題和b小題...麻煩了.. [Hint] Try to solve the problem yourself first then people will be more willing to help you. Trust me, you can do it. --

※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 114.32.184.86 ※ 編輯: Entropy1988 來自: 114.32.184.86 (11/06 17:46) (經HDT與我協調，取消HDT的推文) ※ 編輯: Entropy1988 來自: 114.32.184.86 (11/06 22:11)