<p> 求证:<br /> <img src="https://img.ppkao.com/2019-04/wangxuan/2019041516384661675.jpg" /></p>
A、求证:
A、求证:
A、对于体积V内N个电子的自由电子气体,求证:<br /> (1)电子气体的压强p=(2/3)×(U<sub>0sub>/V)其中U<sub>0sub>为电子气体的基态能量。<br /> (2)体弹性模量<img src="https://img.ppkao.com/2019-04/wanxiaokui/2019041916480024144.jpg" />为10U<sub>0sub>/9V。
A、如果算符<img src="https://img.ppkao.com/2019-04/liyunao/2019041013301694278.jpg" />满足<img src="https://img.ppkao.com/2019-04/liyunao/2019041013303038509.jpg" />关系式,求证<br /> <img src="https://img.ppkao.com/2019-04/liyunao/2019041013303655462.jpg" />
A、图示电路中,U=220V,S闭合时,U<sub>Rsub>=80V,P=320W;S断开时,P=405W,电路为电感性,求R、L<sub>Xsub>和C<sub>Xsub>。<br /> <img src="https://img.ppkao.com/2018-09/tangxueping/2018093016472464610.jpg" />
A、A.<img src="https://img.ppkao.com/2019-04/xiaotian/2019041517035379211.jpg" /><br /> B.<img src="https://img.ppkao.com/2019-04/xiaotian/2019041517035733869.jpg" /><br /> C.<img src="https://img.ppkao.com/2019-04/xiaotian/2019041517040187655.jpg" /><br /> D.<img src="https://img.ppkao.com/2019-04/xiaotian/2019041517040430083.jpg" />
A、A.F=KΔp<br /> B.ΔP=kF<br /> C.ΔP=k<img src="https://img.ppkao.com/2017-08/zhangyijie/2017082710164399649.jpg" /><br /> D.F=k
A、设X=(X1,…Xp)′的协方差阵(p×p)为<img src="https://img.ppkao.com/2018-10/wangjing/2018100917075243497.jpg" />,0<p<1<br>证明:λ1=σ<sup>2sup>[1-ρ(1-ρ)]为最大特征根,其对应的主成分为<img src="https://img.ppkao.com/2018-10/wangjing/2018100917073511194.jpg" />p<1<br>
A、如题图所示,设B点发出的平面横波沿BP方向传播,它在B点的振动方程为<img src="https://img.ppkao.com/2019-04/liyunao/2019041616333460033.jpg" /><br /> C点发出的平面横波沿CP方向传播,它在C点的振动方程为<img src="https://img.ppkao.com/2019-04/liyunao/2019041616334242069.jpg" />,本题中Y以m计,t以s计.设BP=0.4m,CP=0.5m,波速u=0.2m·s<sup>-1sup><br /> <img src="https://img.ppkao.com/2019-04/liyunao/2019041616332795297.jpg" />
A、完成下列反应 <br /> (a) P<sub>4sub>+HNO<sub>3sub><img src="https://img.ppkao.com/2019-04/wangjing/2019041416320257508.jpg" /><br /> (b) AsCl<sub>3sub>+H<sub>2sub>O<img src="https://img.ppkao.com/2019-04/wangjing/2019041416320257508.jpg" /> <br /> (c) POCl<sub>3sub>+H<sub>2sub>O<img src="https://img.ppkao.com/2019-04/wangjing/2019041416320257508.jpg" /> <br /> (d) P<sub>4sub>O<sub>10sub>+H<sub>2sub>O<img src="https://img.ppkao.com/2019-04/wangjing/2019041416320257508.jpg" />  <br /> (e) P<sub>4sub>O<sub>6sub>+H<sub>2sub>O<img src="https://img.ppkao.com/2019-04/wangjing/2019041416320257508.jpg" /> <br /> (f) Zn<sub>3sub>P<sub>2sub>+HCl(稀)<img src="https://img.ppkao.com/2019-04/wangjing/2019041416320257508.jpg" />
A、A.<img src="https://img.ppkao.com/2019-04/xiaotian/2019042917175712037.jpg" /><br /> B.<img src="https://img.ppkao.com/2019-04/xiaotian/2019042917180085132.jpg" /><br /> C.<img src="https://img.ppkao.com/2019-04/xiaotian/2019042917180310884.jpg" /><br /> D.<img src="https://img.ppkao.com/2019-04/xiaotian/2019042917180684437.jpg" />