0)1.01*105*0.671.76*104*0.858.471*104N3.17解:由题意如图建立坐标系,可得:V0qV0V2qV2V1qV1由连续方程得到qV1qV2qV0又V1V2V3X方向可得FxV0qV0sinY方向可得V0qV0cosqV1V1V2qV291cosqqV12V0解得1cosqqV22V03.18解:由题意,可得:VA1V2A2V3A330.48*0.00933.048*0.08307V3(0.00930.0837)30.48*0.00933.048*0.0837V1.9*3.0485.791230.093222则由动量方程可解得P3A3P2A2P1A1V3A3V1A1V2A2222P3P1(V3A3V1A1V2A2)/A36975.8Pa3.19解:①由题意如图建立坐标系,不计压强可得:2FxP1A1P2A2cos2V2A2V2cos1V1A1V1FXVA(cos1)2FyP2A2sin2V2A2V2sin0FyVAsin②如图建立坐标系,可得:222FxA(Vu)cosA(Vu)A(Vu)(cos1)F则功率wFuFu当0时,取最大值则u/V1/3xu3.20解:由题意PPV21.01*1050.5*1.225*12229.22*104PBa2a2PPV1.01325*1050.5*1.225*6129.90*104PB2a22a3.21解:设发动机壳体为控制体作用在壳体上的压强为Pa,出口压强为Pe沿x方向PaAePeAeRqmVjRqmVjPaAePeAeqmVj(PePa)Ae推力F=-R方向:向左实验台所受之力水平向右10