理论力学参考补充例题2.ppt

xFF 2F o 1y 3z 且三力大小均为 F,求此力系向 O点简化的结果。 321FFF,,例:正方体各边长均为 a,作用有,如图所示。 1 1 1 1 1 3 3 3 3 3 3 , 3 3 x y z F F F F F F F ? ? ??? ?? 2 2 2 2 0 , 2 x y z F F F F ? ?? 3 3 3 2 , 0 2 x z y F F F F ? ? ?解: 3 2 3 2 3 2 3 2 3 2 3 F F F ? ?????? ? ????? ?????? ?????? ????? R F i j k Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. xFF 2F o 1y 3z 3 3 ( ) , ( ) , ( ) 0 3 3 x y z M Fa M Fa M ?? ?? 1 1 1 F F F 2 2 2 2 2 ( ) 0, ( ) , ( ) 2 2 x y z M M Fa M Fa ? ?? ? F F F 3 3 2 2 2 ( ) , ( ) 0, ( ) 2 2 x y z M Fa M M Fa ? ??? F F F 2 3 3 2 2 3 3 2 O Fa Fa ? ???? ? ??? ???? ???? ??? M i j Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 向O点简化的结果为: 3 2 3 2 3 2 3 2 3 2 3 F F F ? ?????? ? ????? ?????? ?????? ????? R F i j k 2 3 3 2 2 3 3 2 O Fa Fa ? ???? ? ??? ???? ???? ??? M i j Evaluation only. Evaluation only. Created with Client Profile .