20春学期《工程力学X》在线平时作业2

adminhan

<p>选择题3：</p><p><img alt="" width="393" height="114" src="http://file.open.com.cn/ItemDB/43582/7dcd3328-0c28-40e7-b602-e92865b9492e/2009519202732939.png" /></p>
A:A
B:B
C:C
D:D

<p>选择题2</p><p><img alt="" width="356" height="59" src="http://file.open.com.cn/ItemDB/43582/fd2eac1b-a5a5-4bed-a8b0-9cff800f07ce/2009519203927267.png" /></p>
A:A
B:B
C:C
D:D

<p>选择题3</p><p><img alt="" width="397" height="201" src="http://file.open.com.cn/ItemDB/43582/9f07057f-1521-4f8e-b6c4-1bac094fc61a/2009519202156549.png" /></p>
A:A
B:B
C:C
D:D

<p>选择题2</p><p><img alt="" width="381" height="57" src="http://file.open.com.cn/ItemDB/43582/294e476b-5000-4a50-bba3-b5e48aa64495/2009519202041142.png" /></p>
A:A
B:B
C:C
D:D

<p>选择题4：</p><p><img alt="" width="422" height="117" src="http://file.open.com.cn/ItemDB/43582/72e02de6-8a75-46e9-98c1-232c094cf840/200951920215752.png" /></p>
A:<p>A</p>
B:B
C:C
D:D

<p>选择题1</p><p><img alt="" src="http://file.open.com.cn/ItemDB/43582/a48d4f5a-6e1f-43d9-8c13-b91c70f8fe26/2009519202523736.png" /></p>
A:A
B:B
C:C
D:D

<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">两个主应力不为零是</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; TEXT-DECORATION: underline; mso-spacerun: 'yes'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">应力状态，三个主应力不为零是</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; TEXT-DECORATION: underline; mso-spacerun: 'yes'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">应力状态。</span></p><!--EndFragment-->
A:<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">平面、空间；</span></p><!--EndFragment-->
B:<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">平面、</span>平面</span></p><!--EndFragment-->
C:<span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">空间、平面</span>
D:<span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">空间、<span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">空间、</span></span>

<p>内力为零的杆件成为虚杆，试判断下图所示桁架中零杆的个数，下列答案中那个正确</p><p><img alt="" width="334" height="214" src="http://file.open.com.cn/ItemDB/43582/34742c6e-75c1-4465-89b0-805e97aa0a60/20095182103758.png" /></p>
A:一个
B:两个
C:三个
D:四个

<div>力<img alt="" width="16" height="25" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/2009519192711174.gif" />和力<img alt="" width="17" height="25" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/2009519192733158.gif" />的合力为<img alt="" width="19" height="25" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/2009519192754111.gif" /><span>, <img alt="" width="75" height="25" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/2009519192818377.gif" />, </span>它们之间的大小关系，可能属于下列哪种情况</div><div>A必有<img alt="" width="75" height="25" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/2009519192851533.gif" /></div><div><div>B必有<img alt="" width="47" height="24" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/200951919292549.gif" />且<img alt="" width="48" height="24" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/2009519192942674.gif" /></div><div><div>C必有<img alt="" width="47" height="24" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/200951919305236.gif" />且<img alt="" width="49" height="24" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/2009519193033752.gif" /></div><div>D可能有<img alt="" width="48" height="24" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/200951919312658.gif" />且<img alt="" width="47" height="24" src="http://file.open.com.cn/ItemDB/43582/15041461-7950-462a-96b9-7d21faabbd04/200951919327267.gif" /></div></div></div>
A:<div><span style="FONT-FAMILY: 'Times New Roman'; FONT-SIZE: 12pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体" lang="EN-US"><span style="POSITION: relative; TOP: 6pt; mso-text-raise: -6.0pt"><v:shapetype id="_x0000_t75" stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600">&nbsp;A<v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype></span></span></div>
B:<div>B</div>
C:<div>C</div>
D:<p>D</p>

<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">剪切面平行与剪力，挤压面垂直与挤压力。（&nbsp;&nbsp;&nbsp;）</span></p><!--EndFragment-->
A:对
B:错

<p>选择题2</p><p><img alt="" width="408" height="151" src="http://file.open.com.cn/ItemDB/43582/910b70ee-11df-4afc-a5e4-52a5931b6fdf/2009519203211799.png" /></p>
A:A
B:B
C:C
D:D

<p>选择3：</p><p><img alt="" width="402" height="75" src="http://file.open.com.cn/ItemDB/43582/8c5fbadb-04fb-449b-8153-859b3384f273/200951919581689.png" /></p>
A:A
B:B
C:C
D:D

<p>选择题1</p><p><img alt="" width="400" height="77" src="http://file.open.com.cn/ItemDB/43582/0ce00dce-abdd-47f2-8500-d9211df9879e/200951920308502.png" /></p><p><img alt="" width="211" height="67" src="http://file.open.com.cn/ItemDB/43582/0ce00dce-abdd-47f2-8500-d9211df9879e/2009519203030892.png" /></p>
A:A
B:B
C:C
D:D

<p>选择题2</p><p><img alt="" width="400" height="159" src="http://file.open.com.cn/ItemDB/43582/b36caff0-b86b-4935-9dde-57f385b7329d/2009519202648111.png"></p>
A:A
B:B
C:C
D:D

<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">挤压和压缩变形是相同的。（&nbsp;&nbsp;&nbsp;）</span></p><!--EndFragment-->
A:对
B:错

<div align="left">将构件的许用挤压应力和许用压应力的大小进行对比，可知( )，因为挤压变形发生在局部范围，而压缩变形发生在整个构件上。 </div>
A:前者要小些
B:前者要大些
C:二者大小相等
D:二者可大可小

<div>平面汇交力系的必要和充分条件是各力在两个坐标轴上投影的代数和</div><div>&nbsp;</div>
A:&nbsp;都等于0&nbsp;&nbsp;
B:&nbsp;&nbsp;&nbsp;都小于0&nbsp;&nbsp;
C:&nbsp;&nbsp;都大于0
D:&nbsp;&nbsp;&nbsp;一个大于0，一个小于0&nbsp;&nbsp;&nbsp;

<p>选择2：</p><p><img alt="" src="http://file.open.com.cn/ItemDB/43582/9383f732-4246-4866-8734-a3671502d5af/2009519195648971.png" /></p><p><img alt="" width="318" height="127" src="http://file.open.com.cn/ItemDB/43582/9383f732-4246-4866-8734-a3671502d5af/200951919575689.png" /></p>
A:A
B:B
C:C
D:D

<p>选择题1</p><p><img alt="" src="http://file.open.com.cn/ItemDB/43582/497e2686-138c-4ca8-9933-ace234ebecea/2009519203626939.png" /></p>
A:A
B:B
C:C
D:D

<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">合力投影定理建立了合力投影与分力投影的关系。（&nbsp;&nbsp;&nbsp;&nbsp;）</span></p><!--EndFragment-->
A:对
B:错

<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">在平行移轴公式</span><span style="FONT-STYLE: italic; FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">I</span><span style="FONT-STYLE: italic; FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; VERTICAL-ALIGN: sub; mso-spacerun: 'yes'">z</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; VERTICAL-ALIGN: sub; mso-spacerun: 'yes'">1</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">=</span><span style="FONT-STYLE: italic; FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">I</span><span style="FONT-STYLE: italic; FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; VERTICAL-ALIGN: sub; mso-spacerun: 'yes'">z</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">+</span><span style="FONT-STYLE: italic; FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">a</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; VERTICAL-ALIGN: super; mso-spacerun: 'yes'">2</span><span style="FONT-STYLE: italic; FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">A</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">中，</span><span style="FONT-STYLE: italic; FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">z</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">轴和<font face="Times New Roman">z</font></span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; VERTICAL-ALIGN: sub; mso-spacerun: 'yes'">1</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">轴</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; TEXT-DECORATION: underline; mso-spacerun: 'yes'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">，<font face="Times New Roman">z</font><font face="宋体">轴通过</font></span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; TEXT-DECORATION: underline; mso-spacerun: 'yes'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">。</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'"><o:p></o:p></span></p><!--EndFragment-->
A:<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">平行、中性轴；</span></p><!--EndFragment-->
B:<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">平行、下边缘；&nbsp;</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'"><o:p></o:p></span></p><!--EndFragment-->
C:<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">垂直、中性轴；&nbsp;</span></p><!--EndFragment-->
D:<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">垂直、下边缘</span><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">.</span></p><!--EndFragment-->

<div>边长为a的立方框架上，沿对角线AB作用一力，其大小为P；沿CD边作用另一力，其大小为1.732P/3，此力系向O点简化的主矩大小为</div><div><img alt="" width="464" height="523" src="http://file.open.com.cn/ItemDB/43582/f4bc4c9a-9927-44e4-a762-cb163d7d222c/2009518212443683.png" /></div>
A:2.449Pa
B:1.732Pa；
C:2.449Pa/6；
D:1.732Pa/3。

<div><span>作用在同一物体上的两个力，大小相等，方向相反的力可能是</span></div>
A:<div><span>一对平衡力　　</span></div>
B:<div><span>一个力偶</span><span>;</span><br /></div>
C:<span>一对平衡力或一个力偶</span><span>;</span><br />
D:<span>一对作用力和反作用力</span><span>;</span>

<span style="FONT-FAMILY: 宋体; FONT-SIZE: 12pt; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">下列说法正确的是</span>
A:<div>分力一定小于合力</div>
B:<div>分力一定大于合力</div>
C:<div>分力一定等于合力</div>
D:分力与合力的大小关系不一定

<p style="MARGIN-TOP: 0pt; MARGIN-BOTTOM: 0pt" class="p0"><span style="FONT-FAMILY: '宋体'; FONT-SIZE: 10.5pt; mso-spacerun: 'yes'">如果两个粗糙接触面间有正压力作用，该接触面间一定出现摩擦力。（&nbsp;&nbsp;&nbsp;&nbsp;）</span></p><!--EndFragment-->
A:对
B:错