(2points)(2points)AnswersPartIQ1.Theplaneshouldfollowtheparabola飞机须沿抛物线运动x=vtcos0,y=vtsin0-2gt2(3points)Q2(6points)Iw=T••Thecenteroftherodwillnotmoveinthehorizontaldirection杆中心在水平方向不动。ml2l7I=+2m(—)2=ml212212Therearetwowaystofindthetorque.找力距的方法有两种。Method-1方法-1Theforcesactingupontherodareshown.Thetorquetothecenteroftherodis由如图力的分析,可得l3lT=-(2mg+mg)刁0=—mg—0.Method-2方法-2Givenasmallangledeviation0fromequilibrium,thepotentialenergyis给定一个角度的小位移0,势能为3l3lmg—(1-cos0)口mg—02.
