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		<title>Statistical Mechanics - new forum threads</title>
		<link>http://statmech.wikidot.com/forum/start</link>
		<description>Threads in forums of the site &quot;Statistical Mechanics&quot;</description>
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				<guid>http://statmech.wikidot.com/forum/t-143820</guid>
				<title>can you please post solutions to problems 1,2,4 and 10 fr Ch 6?</title>
				<link>http://statmech.wikidot.com/forum/t-143820/can-you-please-post-solutions-to-problems-1-2-4-and-10-fr-ch-6</link>
				<description></description>
				<pubDate>Thu, 02 Apr 2009 08:03:51 +0000</pubDate>
				<wikidot:authorName>poynting</wikidot:authorName>				<wikidot:authorUserId>307523</wikidot:authorUserId>				<content:encoded>
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						 <p>please do! thanks a lot!</p> 
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				<guid>http://statmech.wikidot.com/forum/t-143819</guid>
				<title>can anyone please post solutions to questions 3,7,13, and 14 in Ch 5?</title>
				<link>http://statmech.wikidot.com/forum/t-143819/can-anyone-please-post-solutions-to-questions-3-7-13-and-14-in-ch-5</link>
				<description></description>
				<pubDate>Thu, 02 Apr 2009 08:02:22 +0000</pubDate>
				<wikidot:authorName>poynting</wikidot:authorName>				<wikidot:authorUserId>307523</wikidot:authorUserId>				<content:encoded>
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						 <p>please! thank you! i badly need them.</p> 
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				<guid>http://statmech.wikidot.com/forum/t-133074</guid>
				<title>sorry doubt above problems in &quot;fundamentals of statistical and thermal physics&quot; of F.Reif</title>
				<link>http://statmech.wikidot.com/forum/t-133074/sorry-doubt-above-problems-in-fundamentals-of-statistical-and-thermal-physics-of-f-reif</link>
				<description></description>
				<pubDate>Tue, 24 Feb 2009 03:40:45 +0000</pubDate>
				<wikidot:authorName>sursum</wikidot:authorName>				<wikidot:authorUserId>288356</wikidot:authorUserId>				<content:encoded>
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						 <p>in problems 1.4, 1.7 and 1.9!!!</p> <p>thnxs!!!!</p> 
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				<guid>http://statmech.wikidot.com/forum/t-101092</guid>
				<title>Problem 12-7</title>
				<link>http://statmech.wikidot.com/forum/t-101092/problem-12-7</link>
				<description></description>
				<pubDate>Thu, 30 Oct 2008 02:06:44 +0000</pubDate>
				<wikidot:authorName>smnhasan</wikidot:authorName>				<wikidot:authorUserId>230052</wikidot:authorUserId>				<content:encoded>
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						 <p>Can any one please solve it for me?</p> 
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				<guid>http://statmech.wikidot.com/forum/t-93072</guid>
				<title>Solution: Problem1-46</title>
				<link>http://statmech.wikidot.com/forum/t-93072/solution:problem1-46</link>
				<description></description>
				<pubDate>Mon, 29 Sep 2008 12:55:55 +0000</pubDate>
				<wikidot:authorName>siroma</wikidot:authorName>				<wikidot:authorUserId>207340</wikidot:authorUserId>				<content:encoded>
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						 <span class="equation-number">(1)</span> <div class="math-equation" id="equation-421180-1"><img src="http://statmech.wikidot.com/local--math/eqs/9d178fdcd4e30abc23b30b7a8efbe946.png" alt="W(X,Y)=X+Y" /></div> <h5><span>Expected value of W:</span></h5> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-421180-2"><img src="http://statmech.wikidot.com/local--math/eqs/e052d913a187dcf00daa691a2ec537c9.png" alt="\begin{tabular}{ccl} E(W) &amp; \stackrel{\text{by def.}}{=} &amp; \iint{(x+y)f(x,y)dxdy \ &amp; = &amp; \iint{xf(x,y)dxdy} + \iint{yf(x,y)dxdy \ &amp; \stackrel{\text{indep.} }{=} &amp; \iint{xf_1(x)f_2(y)dxdy + \iint{yf_1(x)f_2(y)dxdy\ &amp; = &amp;\int{xf_1(x)dx}\int{f_2(y)dy} + \int{yf_2(y)dy}\int{f_1(x)dx}\ &amp; = &amp;\int{xf_1(x)dx} + \int{yf_2(y)dy}\ &amp; = &amp; E(X)+ E(Y) \end{tabular}" /></div> <h5><span>Variance of W:</span></h5> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-421180-3"><img src="http://statmech.wikidot.com/local--math/eqs/65f30860a430c8763258dea0b90a16fd.png" alt="\begin{tabular}{ccl} Var(W) &amp; \stackrel{\text{by def.}}{=} &amp; \iint{((x+y)-E(X+Y)})^2}f(x,y)dxdy \ &amp; = &amp; \iint{((x-E(X))+(y-E(Y)))^2f(x,y)dxdy} \ &amp; = &amp; \iint{(x-E(X))^2f(x,y)dxdy + \\ &amp; &amp; 2\iint{(x-E(X))(y-E(Y))}f(x,y)dxdy + \ &amp; &amp; \iint{(y-E(Y))f(x,y)dxdy\ &amp; \stackrel{\text{indep.} }{=} &amp; \int{(x-E(X))^2f_1(x)dx\int{f_2(y)dy} +\ &amp; &amp; 2\int{(x-E(x))f_1(x)dx}\int{(y-E(y))f_2(y)dy}+\\ &amp; &amp; \int{(y-E(Y))^2f_2(y)dy\int{f_1(x)dx}\ &amp; = &amp; Var(X) + Var(Y) \end{tabular}" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-92018</guid>
				<title>Solution: Problem1-57</title>
				<link>http://statmech.wikidot.com/forum/t-92018/solution:problem1-57</link>
				<description></description>
				<pubDate>Thu, 25 Sep 2008 10:45:19 +0000</pubDate>
				<wikidot:authorName>siroma</wikidot:authorName>				<wikidot:authorUserId>207340</wikidot:authorUserId>				<content:encoded>
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						 <p>Geometric progression sum formula derivation:</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-404977-1"><img src="http://statmech.wikidot.com/local--math/eqs/6565326f9fb47a40a909db2b21cf9f2d.png" alt="S_n=\sum_{n=0}^\infty {q^{n}a_0}=a_0+qa_0+q^2a_0+...+q^na_0" /></div> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-404977-2"><img src="http://statmech.wikidot.com/local--math/eqs/c9913c32ae1f4a8c1dec5d50a2063b35.png" alt="qS_n=q\sum_{n=0}^\infty {q^na_0}=qa_0+q^2a_0+q^3a_0+...+q^{n+1}a_0" /></div> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-404977-3"><img src="http://statmech.wikidot.com/local--math/eqs/09ad4448a73d65c5cd88acde4ea13116.png" alt="(q-1)S_n=q^{n+1}a_0-a_0" /></div> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-404977-4"><img src="http://statmech.wikidot.com/local--math/eqs/3afb2b7261bf4a61e01eb165133b4a6b.png" alt="S_n=a_0\frac{q^{n+1}-1}{q-1}" /></div> <p>If q&lt;1 then</p> <span class="equation-number">(5)</span> <div class="math-equation" id="equation-404977-5"><img src="http://statmech.wikidot.com/local--math/eqs/7896e7623963e3a5ad0cb4ad8383fe19.png" alt="\lim_{n \to \infty } S_n = a_0\frac{1}{1-q}" /></div> <p>In the problem <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/268ce8e07328740ad8eccbaf334d8381.png" alt="a_0=1" /> and <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/4babfa40fc55885392a0558b5dd8c7f0.png" alt="q=e^{-\alpha}" /> therefore we require that <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/e1db1decbe66691c2048430f81ec3d67.png" alt="e^{-\alpha} &lt; 1" />; thus when <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/315c82a57164f0e70880d5170b94a4d4.png" alt="\alpha&gt;0" /> we have closed sum</p> <span class="equation-number">(6)</span> <div class="math-equation" id="equation-404977-6"><img src="http://statmech.wikidot.com/local--math/eqs/c8b9f7cd442b8ba88d4d5c1f03d32cd7.png" alt="\lim_{n \to \infty } S_n = \frac{1}{1-e^{-\alpha}}" /></div> <p>On the other hand,</p> <span class="equation-number">(7)</span> <div class="math-equation" id="equation-404977-7"><img src="http://statmech.wikidot.com/local--math/eqs/b701dfa7ed04d007b8293f2c4caaa7be.png" alt="I=\int_{0}^{\infty}{e^{-\alpha n}}dn = -\frac{e^{-\alpha n}}{\alpha} |_0^\infty = -\frac{1}{\alpha}(\lim_{n \to \infty} e^{-\alpha n} - 1)" /></div> <p>Because <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/315c82a57164f0e70880d5170b94a4d4.png" alt="\alpha&gt;0" /></p> <span class="equation-number">(8)</span> <div class="math-equation" id="equation-404977-8"><img src="http://statmech.wikidot.com/local--math/eqs/a47a2f765db923e2e5b33e71520025a5.png" alt="I = \frac{1}{\alpha}" /></div> <p>To find required <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/7b7f9dbfea05c83784f8b85149852f08.png" alt="\alpha" /> we have</p> <span class="equation-number">(9)</span> <div class="math-equation" id="equation-404977-9"><img src="http://statmech.wikidot.com/local--math/eqs/f60f9ae0aec8d0d90014cfeba19bdbb7.png" alt="\frac{1}{\alpha}=\frac{1}{1-e^{-\alpha}}" /></div> <p>or</p> <span class="equation-number">(10)</span> <div class="math-equation" id="equation-404977-10"><img src="http://statmech.wikidot.com/local--math/eqs/7618966505373d5e627c71b249a2ba54.png" alt="e^{-\alpha}=1-\alpha" /></div> <p>Equation (10) has only one solution(this can be shown comparing derivatives of rhs and lhs functions):</p> <span class="equation-number">(11)</span> <div class="math-equation" id="equation-404977-11"><img src="http://statmech.wikidot.com/local--math/eqs/4532691ab0bf97d179fca720a67191ab.png" alt="\alpha=0" /></div> <p>To satisfy requirement of <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/105eff5d63f81d987ca1ef3ab59e20e4.png" alt="\alpha &gt; 0" /> we give result in limit form:</p> <span class="equation-number">(12)</span> <div class="math-equation" id="equation-404977-12"><img src="http://statmech.wikidot.com/local--math/eqs/df77b6f28c856b92ab930138e67ec95e.png" alt="I \to S \text{ when } \alpha \to 0^+" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-91938</guid>
				<title>Solution: Problem1-55</title>
				<link>http://statmech.wikidot.com/forum/t-91938/solution:problem1-55</link>
				<description></description>
				<pubDate>Thu, 25 Sep 2008 02:09:39 +0000</pubDate>
				<wikidot:authorName>siroma</wikidot:authorName>				<wikidot:authorUserId>207340</wikidot:authorUserId>				<content:encoded>
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						 <dl> <dt>Even function</dt> <dd>f(x)=f(-x)</dd> </dl> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-728364-1"><img src="http://statmech.wikidot.com/local--math/eqs/f342f2371a607b815b3997557bf74577.png" alt="f(-x)=\frac{e^{-x}}{(1 \pm e^{-x})^2}=\frac{e^{-x}}{(1\pm\frac{1}{e^x})^2}=\frac{e^{-x}e^{2x}}{(e^x\pm1)^2}=\frac{e^x}{(1 \pm e^x)^2}=f(x)" /></div> <p>QED</p> 
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				<guid>http://statmech.wikidot.com/forum/t-91934</guid>
				<title>Solution: Problem1-30</title>
				<link>http://statmech.wikidot.com/forum/t-91934/solution:problem1-30</link>
				<description></description>
				<pubDate>Thu, 25 Sep 2008 01:27:58 +0000</pubDate>
				<wikidot:authorName>siroma</wikidot:authorName>				<wikidot:authorUserId>207340</wikidot:authorUserId>				<content:encoded>
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						 <h1><span>Part 1</span></h1> <hr /> <p>1st law:</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-424176-1"><img src="http://statmech.wikidot.com/local--math/eqs/c764acf6451d3a5a77d621bb92bf85af.png" alt="du=\delta{Q}+\delta{W}=Tds-Pdv" /></div> <p>Enthalpy definition:</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-424176-2"><img src="http://statmech.wikidot.com/local--math/eqs/f20675e6b5d5cb7827aaa6215ad56942.png" alt="h=u+Pv" /></div> <p>Enthalpy differential:</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-424176-3"><img src="http://statmech.wikidot.com/local--math/eqs/7b4a33e7313ed4bc56e693a5e9ad14b2.png" alt="dh=du+Pdv+vdP=Tds+vdP" /></div> <p>Maxwell equation from (2):</p> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-424176-4"><img src="http://statmech.wikidot.com/local--math/eqs/8f18471b98302bf76bbe3dfd828d1efd.png" alt="(\frac{\partial{T}}{\partial{P}})_v=(\frac{\partial{v}}{\partial{s}})_T" /></div> <p>Definition of heat capacity and insertion (1) into definition:</p> <span class="equation-number">(5)</span> <div class="math-equation" id="equation-424176-5"><img src="http://statmech.wikidot.com/local--math/eqs/171d7a45e52b4ff8540c0deba2240a04.png" alt="c_v=(\frac{\partial{u}}{\partial{T}})_v=T(\frac{\partial{s}}{\partial{T}})_v" /></div> <p>Write entropy as function of T and v:</p> <span class="equation-number">(6)</span> <div class="math-equation" id="equation-424176-6"><img src="http://statmech.wikidot.com/local--math/eqs/e8e5177f81bd24174b4edeea91d964ae.png" alt="s=s(T,v)" /></div> <p>Derive expression for entropy differential and use (4) and (5):</p> <span class="equation-number">(7)</span> <div class="math-equation" id="equation-424176-7"><img src="http://statmech.wikidot.com/local--math/eqs/ab9bf8da0e6a4ec938b08ba36e80f6da.png" alt="ds=(\frac{\partial{s}}{\partial{T}})_vdT+(\frac{\partial{s}}{\partial{v}})_T=\frac{c_v}{T}dT+(\frac{\partial{P}}{\partial{T}})_vdv" /></div> <p>Insert (7) into (1):</p> <span class="equation-number">(8)</span> <div class="math-equation" id="equation-424176-8"><img src="http://statmech.wikidot.com/local--math/eqs/aa63cadfc4f2ad60989d6ede499c24f2.png" alt="du=\delta{Q}+\delta{W}=Tds-Pdv=T(\frac{c_v}{T}dT+(\frac{\partial{P}}{\partial{T}})_vdv)-Pdv=(T(\frac{\partial{P}}{\partial{T}})_v -P)+c_vdT" /></div> <p>QED</p> <h1><span>Part 2</span></h1> <hr /> <p>van der Waals equation:</p> <span class="equation-number">(9)</span> <div class="math-equation" id="equation-424176-9"><img src="http://statmech.wikidot.com/local--math/eqs/690250e0ea0c59d06c62075fa393d681.png" alt="(p+\frac{a}{v^2})(v-b)=kT" /></div> <p>Express p:</p> <span class="equation-number">(10)</span> <div class="math-equation" id="equation-424176-10"><img src="http://statmech.wikidot.com/local--math/eqs/1b4aad97db1a11c13dc12ffd0c8dcc14.png" alt="p=\frac{kT}{v-b}-\frac{a}{v^2}" /></div> <p>At constant T equation (8) becomes:</p> <span class="equation-number">(11)</span> <div class="math-equation" id="equation-424176-11"><img src="http://statmech.wikidot.com/local--math/eqs/ccf606977eec69d987759761289b9075.png" alt="(\frac{\partial{u}}{\partial{v}})_T=T(\frac{\partial{P}}{\partial{T}})_v-p" /></div> <p>Differentiate (10) at constant v and put into (11):</p> <span class="equation-number">(12)</span> <div class="math-equation" id="equation-424176-12"><img src="http://statmech.wikidot.com/local--math/eqs/ab006c3b1dd46516e8731f3a316444d8.png" alt="T(\frac{\partial{P}}{\partial{T}})_v-p=\frac{kT}{v-b}-p=\frac{a}{v^2}" /></div> <p>QED</p> 
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				<guid>http://statmech.wikidot.com/forum/t-90281</guid>
				<title>including pdf documents</title>
				<link>http://statmech.wikidot.com/forum/t-90281/including-pdf-documents</link>
				<description></description>
				<pubDate>Fri, 19 Sep 2008 09:58:01 +0000</pubDate>
				<wikidot:authorName>juliantalbot</wikidot:authorName>				<wikidot:authorUserId>4149</wikidot:authorUserId>				<content:encoded>
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						 <p>pdf documents can be incorporated in posts.</p> 
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				<guid>http://statmech.wikidot.com/forum/t-44274</guid>
				<title>solution</title>
				<link>http://statmech.wikidot.com/forum/t-44274/solution</link>
				<description></description>
				<pubDate>Sat, 01 Mar 2008 19:08:07 +0000</pubDate>
				<wikidot:authorName>deepali</wikidot:authorName>				<wikidot:authorUserId>90073</wikidot:authorUserId>				<content:encoded>
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						 <p>can somebody post 1-51</p> 
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				<guid>http://statmech.wikidot.com/forum/t-28386</guid>
				<title>Problem 10,19,20</title>
				<link>http://statmech.wikidot.com/forum/t-28386/problem-10-19-20</link>
				<description></description>
				<pubDate>Sun, 25 Nov 2007 22:47:04 +0000</pubDate>
				<wikidot:authorName>doufas</wikidot:authorName>				<wikidot:authorUserId>50343</wikidot:authorUserId>				<content:encoded>
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						 <p>Does anybody have thoughts on #s 10, 19, or 20?</p> 
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				<guid>http://statmech.wikidot.com/forum/t-26767</guid>
				<title>testing</title>
				<link>http://statmech.wikidot.com/forum/t-26767/testing</link>
				<description></description>
				<pubDate>Tue, 13 Nov 2007 17:45:36 +0000</pubDate>
				<wikidot:authorName>fizzixmom</wikidot:authorName>				<wikidot:authorUserId>49919</wikidot:authorUserId>				<content:encoded>
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						 <p>I'm new to wikidot, and trying to figure out if I need to be a member to post a message. I guess we'll see if this works.</p> 
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				<guid>http://statmech.wikidot.com/forum/t-26504</guid>
				<title>Chapter 2 Questions</title>
				<link>http://statmech.wikidot.com/forum/t-26504/chapter-2-questions</link>
				<description></description>
				<pubDate>Sun, 11 Nov 2007 22:05:07 +0000</pubDate>
				<wikidot:authorName>doufas</wikidot:authorName>				<wikidot:authorUserId>50343</wikidot:authorUserId>				<content:encoded>
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						 <p>Does anybody know #2-2, 2-12 or 2-14?</p> 
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				<guid>http://statmech.wikidot.com/forum/t-24835</guid>
				<title>can anyone help me for the solution5.7</title>
				<link>http://statmech.wikidot.com/forum/t-24835/can-anyone-help-me-for-the-solution5-7</link>
				<description></description>
				<pubDate>Mon, 29 Oct 2007 17:09:22 +0000</pubDate>
				<wikidot:authorName>kal-el</wikidot:authorName>				<wikidot:authorUserId>34367</wikidot:authorUserId>				<content:encoded>
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						 <p>does anybody knowthe solution for 5.7?</p> 
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				<guid>http://statmech.wikidot.com/forum/t-23205</guid>
				<title>help - problem 9</title>
				<link>http://statmech.wikidot.com/forum/t-23205/help-problem-9</link>
				<description></description>
				<pubDate>Mon, 15 Oct 2007 20:39:01 +0000</pubDate>
				<wikidot:authorName>clamarche</wikidot:authorName>				<wikidot:authorUserId>35895</wikidot:authorUserId>				<content:encoded>
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						 <p>Show that the partition function appropriate to an isothermal-isobaric ensemble is</p> <p><img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/fc1e4b1cb8e5f47d764b182f5ac40959.png" alt="delta(N,p,T)=(summation over E)(summation over V)omega(N,V,E)*exp(-E/kT)*exp(-pV/kT)" /></p> <p>Derive the principal thermodynamic connection formulas for this ensemble.</p> <p>When i try to derive the partition function I am getting a term that makes no sense. I was wondering if anyone could help me?</p> <p>thanks</p> 
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				<guid>http://statmech.wikidot.com/forum/t-22329</guid>
				<title>SklogWiki</title>
				<link>http://statmech.wikidot.com/forum/t-22329/sklogwiki</link>
				<description>Addition of &#039;Statistical Mechanics&#039; to SklogWiki WikiNode.</description>
				<pubDate>Mon, 08 Oct 2007 12:32:57 +0000</pubDate>
				<wikidot:authorName>SklogWiki</wikidot:authorName>				<wikidot:authorUserId>41417</wikidot:authorUserId>				<content:encoded>
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						 <p>Dear Statistical Mechanics,</p> <p>I have taken the liberty of adding a link to Statistical Mechanics from the <a href="http://www.sklogwiki.org/SklogWiki/index.php/WikiNode">WikiNode</a> page of <a href="http://www.sklogwiki.org/">www.SklogWiki.org</a>. SklogWiki is a Wiki for people interested in thermodynamics, statistical mechanics, and the computer simulation of materials, in particular liquids and soft condensed matter. See <a href="http://www.sklogwiki.org/SklogWiki/index.php/SklogWiki:About">About SklogWiki</a> for more details. Users of Statistical Mechanics are, of course, more than welcome tocontribute to SklogWiki.</p> <p>All the best,<br /> Dr. Carl McBride.</p> 
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				<guid>http://statmech.wikidot.com/forum/t-21786</guid>
				<title>McQuarrie 1-15</title>
				<link>http://statmech.wikidot.com/forum/t-21786/mcquarrie-1-15</link>
				<description>Does anyone have the solution to this problem?</description>
				<pubDate>Wed, 03 Oct 2007 20:34:39 +0000</pubDate>
				<wikidot:authorName>cv027</wikidot:authorName>				<wikidot:authorUserId>40607</wikidot:authorUserId>				<content:encoded>
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						 <p>I'm trying to solve McQuarrie 1-15, using Kinetic Energy and center of mass theory, and getting nowhere…</p> 
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				<guid>http://statmech.wikidot.com/forum/t-21195</guid>
				<title>posting solutions</title>
				<link>http://statmech.wikidot.com/forum/t-21195/posting-solutions</link>
				<description></description>
				<pubDate>Fri, 28 Sep 2007 04:24:10 +0000</pubDate>
				<wikidot:authorName>kal-el</wikidot:authorName>				<wikidot:authorUserId>34367</wikidot:authorUserId>				<content:encoded>
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						 <p>I am going to post some solutions however is there a easy way to upload it or I just have to write all..</p> 
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				<guid>http://statmech.wikidot.com/forum/t-18620</guid>
				<title>McQuarrie 1-31</title>
				<link>http://statmech.wikidot.com/forum/t-18620/mcquarrie-1-31</link>
				<description>does anyone have the solution for this problem?</description>
				<pubDate>Tue, 04 Sep 2007 23:47:00 +0000</pubDate>
				<wikidot:authorName>kal-el</wikidot:authorName>				<wikidot:authorUserId>34367</wikidot:authorUserId>				<content:encoded>
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						 <p>I am trying to solve McQuarrie 1-31 can anybody help me?</p> 
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				<guid>http://statmech.wikidot.com/forum/t-10305</guid>
				<title>problem 9</title>
				<link>http://statmech.wikidot.com/forum/t-10305/problem-9</link>
				<description></description>
				<pubDate>Fri, 25 May 2007 09:14:38 +0000</pubDate>
				<wikidot:authorName>reza</wikidot:authorName>				<wikidot:authorUserId>19156</wikidot:authorUserId>				<content:encoded>
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						 <p>thanks for your repling</p> 
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				<guid>http://statmech.wikidot.com/forum/t-8291</guid>
				<title>can anyone please solve Q 17 of chapter 12?</title>
				<link>http://statmech.wikidot.com/forum/t-8291/can-anyone-please-solve-q-17-of-chapter-12</link>
				<description>show that for a binary mixture, P/KT = rho(1) + rho(2) + B20(T)*rho(1)^2 + B11(T)* rho(1)*rho(2) + B02*rho(2)^2 +................             
        rho =density(=N/V)
 
                  and find an expression for the coefficients B20(T), B11(T), B02(T).


   again show that if the virial expansion is written in the form
 
                                            P/KT = rho + B2(T)* rho^2+ .......................

     with rho= rho(1) + rho(2) , then

                     B2(x,T)= (x1^2)*B20(T) + x1*(1-x1) * B11(T) + ((1-x1)^2)* B02(T)

   where x1= mole fraction of component 1.</description>
				<pubDate>Wed, 25 Apr 2007 03:46:07 +0000</pubDate>
				<wikidot:authorName>animesh</wikidot:authorName>				<wikidot:authorUserId>16864</wikidot:authorUserId>				<content:encoded>
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						 <p>for a binary gas mixture</p> <p>P/KT = rho(1) + rho(2) + B20(T)*rho(1)^2 + B11(T)* rho(1)*rho(2) + B02*rho(2)^2 +…………….<br /> rho =density(=N/V)</p> <p>and find an expression for the coefficients B20(T), B11(T), B02(T).</p> <p>again show that if the virial expansion is written in the form</p> <p>P/KT = rho + B2(T)* rho^2+ …………………..</p> <p>with rho= rho(1) + rho(2) , then</p> <p>B2(x,T)= (x1^2)*B20(T) + x1*(1-x1) * B11(T) + ((1-x1)^2)* B02(T)</p> <p>where x1= mole fraction of component 1.</p> 
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				<guid>http://statmech.wikidot.com/forum/t-5700</guid>
				<title>Problem 12</title>
				<link>http://statmech.wikidot.com/forum/t-5700/problem-12</link>
				<description></description>
				<pubDate>Thu, 08 Mar 2007 13:24:14 +0000</pubDate>
				<wikidot:authorName>costsab</wikidot:authorName>				<wikidot:authorUserId>11527</wikidot:authorUserId>				<content:encoded>
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						 <p>We evaluate the equation:</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-302559-1"><img src="http://statmech.wikidot.com/local--math/eqs/05c0321d654195dae9e4a3cf071613f2.png" alt="\[\left( {\frac{{\partial E}}{{\partial V}}} \right)_T - T\left( {\frac{{\partial p}}{{\partial T}}} \right)_V = - p\]" /></div> <p>From the thermodynamic potential:</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-302559-2"><img src="http://statmech.wikidot.com/local--math/eqs/3d77a709e3586dbf060aa17bc7dcc181.png" alt="\[dE = TdS - PdV\]" /></div> <p>for constant N (number of molecules) we can write:</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-302559-3"><img src="http://statmech.wikidot.com/local--math/eqs/373916d644aae299d31c28e6608c87e3.png" alt="\[\left( {\frac{{\partial E}}{{\partial V}}} \right)_T = T\left( {\frac{{\partial S}}{{\partial V}}} \right)_T - p\left( {\frac{{\partial V}}{{\partial V}}} \right)_T \]" /></div> <p>And from Maxwell Transformation:</p> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-302559-4"><img src="http://statmech.wikidot.com/local--math/eqs/0a2c6bdc28d977d17788a1ebb6527e12.png" alt="\[\left( {\frac{{\partial E}}{{\partial V}}} \right)_T = T\left( {\frac{{\partial p}}{{\partial T}}} \right)_V - p\]" /></div> <p>By substituting equation (4) into equation (1) we get:</p> <span class="equation-number">(5)</span> <div class="math-equation" id="equation-302559-5"><img src="http://statmech.wikidot.com/local--math/eqs/151fe538c81b6fea62f28b877b327366.png" alt="\[T\left( {\frac{{\partial p}}{{\partial T}}} \right)_V - p - T\left( {\frac{{\partial p}}{{\partial T}}} \right)_V = - p\]" /></div> <p>Which is true as:</p> <span class="equation-number">(6)</span> <div class="math-equation" id="equation-302559-6"><img src="http://statmech.wikidot.com/local--math/eqs/3160cfcb58a13154ace6f4c54c1f1e25.png" alt="\[ - p = - p\]" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-4101</guid>
				<title>Welcome</title>
				<link>http://statmech.wikidot.com/forum/t-4101/welcome</link>
				<description></description>
				<pubDate>Tue, 06 Feb 2007 22:48:54 +0000</pubDate>
				<wikidot:authorName>juliantalbot</wikidot:authorName>				<wikidot:authorUserId>4149</wikidot:authorUserId>				<content:encoded>
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						 <p>McQuarrie's <em>Statistical Mechanics</em> is a classic textbook in the field and, although it was first published in 1976, is still widely used in courses and consulted by researchers. A strong part of the appeal of the book are the numerous problems that accompany each chapter. However, no solution manual is available. The purpose of this site is therefore to serve as a forum where interested students, academics and scientists can submit, consult and discuss solutions to the problems presented in the book.</p> <p>Copies of the book can be ordered directly from the <a href="http://www.uscibooks.com/mcqstatm.htm" >publisher</a>.</p> <p>I welcome you to the site and I encourage you to submit solutions. If you have any questions or would like to moderate one or more chapters, please contact me.</p> <p>Julian Talbot</p> 
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				<guid>http://statmech.wikidot.com/forum/t-3620</guid>
				<title>Problem 16</title>
				<link>http://statmech.wikidot.com/forum/t-3620/problem-16</link>
				<description></description>
				<pubDate>Wed, 24 Jan 2007 18:43:31 +0000</pubDate>
				<wikidot:authorName>plumleyj</wikidot:authorName>				<wikidot:authorUserId>4210</wikidot:authorUserId>				<content:encoded>
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						 <p>f(v) is given in problem 15 and takes the form of</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-827859-1"><img src="http://statmech.wikidot.com/local--math/eqs/0154811bd0f48e48dd603510f6b1676f.png" alt="f(v)=4\pi v^2 \left(\frac {m} {2\pi kT}\right)^\frac 3 2 e^\frac {-mv^2} {2kT}" /></div> <p>The most probable value of the molecular speed occurs when the derivative of the function is equal to 0</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-827859-2"><img src="http://statmech.wikidot.com/local--math/eqs/395f45f5cf28db1746d0d48576606387.png" alt="\begin {flalign*} \frac {\partial f(v)} {\partial v} &amp; = 4\pi \left(\frac {m} {2\pi kT}\right)^\frac 3 2 \left[2v e^\frac {-mv^2} {2kT} + v^2\left(\frac {-mv} {kT} e^\frac {-mv^2} {2kT}\right) \right] \ &amp; = 4\pi \left(\frac {m} {2\pi kT}\right)^\frac 3 2 e^\frac {-mv^2} {2kT} \left[2v + v^2\left(\frac {-mv} {kT} \right) \right] \ &amp; = e^\frac {-mv^2} {2kT}\left[2v + v^2\left(\frac {-mv} {kT} \right) \right] \ &amp; = \left[2+ \left(\frac {-mv^2} {kT} \right) \right] = 0\ \end {flalign*}" /></div> <p>Solving for v;</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-827859-3"><img src="http://statmech.wikidot.com/local--math/eqs/a4bc3fa6aa677049bcd98f04eba8b956.png" alt="v = \left(\frac {2kT} {m}\right)^{\frac 1 2 }" /></div> <p>The mean v is determined, as shown below, where <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/4b89b40b41f266058cddd91cf7d18d79.png" alt="\displaystyle \int_0^\infty x^{2n+1} e^{-ax^2}dx = \frac {n!} {2a^{n+1}}" /> is utilized</p> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-827859-4"><img src="http://statmech.wikidot.com/local--math/eqs/8c046d6e330b1da770712f4cd8826c4c.png" alt="\begin {flalign*} \langle v \rangle = \displaystyle \int f(v)vdv &amp; = \displaystyle \int_0^\infty v 4\pi v^2 \left(\frac {m} {2\pi kT}\right)^\frac 3 2 e^\frac {-mv^2} {2kT} dv \ &amp; = 4\pi \left(\frac {m} {2\pi kT}\right)^\frac 3 2 \left[\frac {2k^2T^2} {m^2}\right] \ &amp; = \left(\frac {8kT} {m \pi} \right)^{\frac 1 2} \end {flalign*}" /></div> <p>The root-mean-square speed is computed as follows, where <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/87a1cb6fe9de86e593e00bff8a584f9b.png" alt="\displaystyle \int_0^\infty x^{2n} e^{-ax^2}dx = \frac{1\cdot 3 \cdot 5 \cdots (2n-1)} {2^{n+1}a^n} \left(\frac \pi a \right) ^\frac 1 2" /> is utilized</p> <span class="equation-number">(5)</span> <div class="math-equation" id="equation-827859-5"><img src="http://statmech.wikidot.com/local--math/eqs/56a5cfcf058c0d03c712a250fc052682.png" alt="\begin {flalign*} \langle v^2 \rangle^\frac 1 2 = \left[ \displaystyle \int f(v)v^2dv \right]^\frac 1 2 &amp; = \left[ \displaystyle \int_0^\infty v^2 4\pi v^2 \left(\frac {m} {2\pi kT}\right)^\frac 3 2 e^\frac {-mv^2} {2kT} dv \right]^\frac 1 2 \ &amp; = \left[4\pi \left(\frac {m} {2\pi kT}\right)^\frac 3 2 \left[\frac 3 2 \left(\frac {2k^5T^5\pi} {m^5}\right)^\frac 1 2 \right] \right]^{\frac 1 2}\ &amp; =\left(\frac {3kT} {m}\right)^{\frac 1 2} \end {flalign*}" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-3271</guid>
				<title>Problem 24</title>
				<link>http://statmech.wikidot.com/forum/t-3271/problem-24</link>
				<description></description>
				<pubDate>Tue, 16 Jan 2007 19:01:22 +0000</pubDate>
				<wikidot:authorName>plumleyj</wikidot:authorName>				<wikidot:authorUserId>4210</wikidot:authorUserId>				<content:encoded>
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						 <p>Show that</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-569128-1"><img src="http://statmech.wikidot.com/local--math/eqs/e4248a4dbee042b9a5bd21252e570d59.png" alt="C_pk_BT^2= \langle H^2 \rangle - \langle H \rangle^2" /></div> <p>In the isothermal-isobaric ensemble, the partition function can be written as</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-569128-2"><img src="http://statmech.wikidot.com/local--math/eqs/cc2d6736500897526d2f92739eccc937.png" alt="\Delta(N,P,T)=\frac{1}{V_o}\int_0^{\infty}dV \sum_i\exp(-\beta(E_i(V)+PV))" /></div> <p>From which the average enthalpy can be obtained as</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-569128-3"><img src="http://statmech.wikidot.com/local--math/eqs/725701a666d5d732d05be98f53bf1cc7.png" alt="\langle H\rangle =-\left(\frac{\partial\ln\Delta}{\partial\beta}\right)_{N,P}" /></div> <p>Therefore</p> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-569128-4"><img src="http://statmech.wikidot.com/local--math/eqs/92d2a0f8f913ced92b96998bf47212c9.png" alt="\begin {flalign*} \langle H^2 \rangle - \langle H \rangle ^2 &amp;= \frac{1}{\Delta}\left(\frac{\partial^2\Delta}{\partial\beta^2}\right)_{N,P} - \frac{1}{\Delta^2}\left(\frac{\partial\Delta}{\partial\beta}\right)^2_{N,P}\ &amp;= \frac{\partial}{\partial\beta}\left(\frac{1}{\Delta}\frac{\partial\Delta}{\partial\beta}\right)_{N,P}\ &amp;=-\frac{\partial}{\partial\beta}\langle H\rangle\ &amp;=k_BT^2C_P \end {falign*}" /></div> <p>where we have used the definitions <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/4e73c57eb981d32545a76e8461542a58.png" alt="\beta=1/K_BT" /> and</p> <span class="equation-number">(5)</span> <div class="math-equation" id="equation-569128-5"><img src="http://statmech.wikidot.com/local--math/eqs/d07e60af36e454596f86b24c0efd4393.png" alt="C_P=\left(\frac{\partial \langle H\rangle}{\partial T}\right)_{N,P}" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-3082</guid>
				<title>Problem 1</title>
				<link>http://statmech.wikidot.com/forum/t-3082/problem-1</link>
				<description></description>
				<pubDate>Thu, 11 Jan 2007 17:08:12 +0000</pubDate>
				<wikidot:authorName>plumleyj</wikidot:authorName>				<wikidot:authorUserId>4210</wikidot:authorUserId>				<content:encoded>
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						 <p>Two forms of the virial expansion are as follows;</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-732542-1"><img src="http://statmech.wikidot.com/local--math/eqs/96cd503bf6399022a1d69904a4753e3f.png" alt="\frac {pV} {RT} = 1 + \frac {B(T)} {V} + \frac {C(T)}{V^2} + ..." /></div> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-732542-2"><img src="http://statmech.wikidot.com/local--math/eqs/1e14fa5eea59a6a5a8b7d5223a0df826.png" alt="\frac {pV} {RT} = 1 + B'(T)p + C'(T)p^2 + ..." /></div> <p>Relations between the two sets of virial coefficients can be determined as follows;</p> <p>First solve equation 1 for p and substitute into equation 2 as follows;</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-732542-3"><img src="http://statmech.wikidot.com/local--math/eqs/f5e90b48b36b7cac193e72e96825f02d.png" alt="\begin {flalign*} \frac {pV} {RT} = &amp; 1 + \frac {B'(T)RT} {V} \left(1 + \frac {B(T)} {V} + \frac {C(T)} {V^2} + ...\right) + \frac {C'(T)RT} {V} \left(1 + \frac {B(T)} {V} + \frac {C(T)} {V^2} + ...\right)^2 + ... \ = &amp; 1 + \frac {B'(T)RT} {V} + \frac {B(T)B'(T)RT} {V^2} + \frac {C(T)B'(T)RT} {V^3}+... +\frac {C'(T)RT} {V} + \frac {2B(T)C'(T)RT} {V^2} + \frac {2C(T)C'(T)RT} {V^3} + \ &amp; \frac {B(T)^2C'(T)RT} {V^3} + \frac {2B(T)C(T)C'(T)RT} {V^3} + ... \end {flalign*}" /></div> <p>Collecting terms within equation 3 with common powers of V,</p> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-732542-4"><img src="http://statmech.wikidot.com/local--math/eqs/83cbd09c7485f67a8c441d7f92f6b85b.png" alt="\frac {pV} {RT} = 1 + \frac {RT} {V} \left[ B'(T) + C'(T)\right] + \frac {B(T)RT} {V^2} \left[B'(T) + 2C'(T)\right] + ..." /></div> <p>In order to write equation 4 as equation 1, the following must be true,</p> <span class="equation-number">(5)</span> <div class="math-equation" id="equation-732542-5"><img src="http://statmech.wikidot.com/local--math/eqs/b01ff078086f99ce3b038df152533b2d.png" alt="\begin {flalign*} B(T) &amp; = RT[B'(T) + C'(T)] \ C(T) &amp; = B(T)RT[(B'(T) + 2C'(T)] \ &amp; = R^2T^2[B'(T)^2 +3B'(T)C'(T)+2C'(T)^2] \end {flalign*}" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-3051</guid>
				<title>Problem 2</title>
				<link>http://statmech.wikidot.com/forum/t-3051/problem-2</link>
				<description></description>
				<pubDate>Wed, 10 Jan 2007 17:06:39 +0000</pubDate>
				<wikidot:authorName>plumleyj</wikidot:authorName>				<wikidot:authorUserId>4210</wikidot:authorUserId>				<content:encoded>
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						 <p>In order to obtain the high temperature limiting form of the heat capacity according to the Einstein model, a A Taylor series expansion of the denominator, truncated at the first order, must be performed;</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-531575-1"><img src="http://statmech.wikidot.com/local--math/eqs/7b5479fbda0053232303e577dd10e4ba.png" alt="C_v = 3Nk\left(\frac {\Theta_E} {T}\right)^2 \frac {e^{\frac {-\Theta_E} {T}}} {\left(1-{e^{\frac {-\Theta_E} {T}}}\right)}" /></div> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-531575-2"><img src="http://statmech.wikidot.com/local--math/eqs/6ed519a59bdbfa197b8771b5c9176b5d.png" alt="\begin {flalign*} \lim_{T\to \infty} C_v &amp; = 3Nk\left(\frac {\Theta_E} {T}\right)^2 \frac {e^{\frac {-\Theta_E} {T}}} {\left(1-{1+ \frac {\Theta_E} {T} }\right)^2} \ &amp; = 3Nk \end {flalign*}" /></div> <p>The low temperature limiting form of the heat capacity according to the Einstein model is as follows;</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-531575-3"><img src="http://statmech.wikidot.com/local--math/eqs/4afaf09fee4da1d3c8e7cd520a93a934.png" alt="\begin {flalign*} \lim_{T\to 0} C_v &amp; = 3Nk\left(\frac {\Theta_E} {T}\right)^2 \frac {e^{\frac {-\Theta_E} {T}}} {1-0} \\ &amp; = 3Nk \left(\frac {\Theta_E} {T}\right)^2 e^{\frac {-\Theta_E} {T}} \end {flalign*}" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-3013</guid>
				<title>Problem 15</title>
				<link>http://statmech.wikidot.com/forum/t-3013/problem-15</link>
				<description></description>
				<pubDate>Tue, 09 Jan 2007 15:10:52 +0000</pubDate>
				<wikidot:authorName>plumleyj</wikidot:authorName>				<wikidot:authorUserId>4210</wikidot:authorUserId>				<content:encoded>
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						 <p>Starting with;</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-821994-1"><img src="http://statmech.wikidot.com/local--math/eqs/cb8f8f13d9b8473b19289623f27cfc4b.png" alt="f(p_x,p_y,p_z)dp_xdp_ydp_z=(2\pi mkT)^{-\frac 3 2}e^{\frac {-p_x^2+p_y^2+p_z^2} {2mkT}}dp_xdp_ydp_z" /></div> <p>Make the proper substitutions provided within the question in order to convert Cartesian coordinates to a spherical polar coordinate representation;</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-821994-2"><img src="http://statmech.wikidot.com/local--math/eqs/c1c780727b298bafdb9bc6ad367b797e.png" alt="f(p)d\bold p=(2\pi mkT)^{-\frac 3 2}e^{\frac {-p^2} {2mkT}} p^2 \sin \theta dp d\theta d\phi" /></div> <p>Integrate equation 2 over all space with respect to <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/2554a2bb846cffd697389e5dc8912759.png" alt="\theta" /> and <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/1ed346930917426bc46d41e22cc525ec.png" alt="\phi" /></p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-821994-3"><img src="http://statmech.wikidot.com/local--math/eqs/242cc494b2d2913e8ce39e3717f20e02.png" alt="\begin {flalign*} f(p)d\bold p &amp; =(2\pi mkT)^{-\frac 3 2}e^{\frac {-p^2} {2mkT}} p^2 dp \displaystyle \int_0^\pi \sin \theta d\theta \int_0^{2\pi} d\phi \\ &amp; =4\pi p^2(2\pi mkT)^{-\frac 3 2}e^{\frac {-p^2} {2mkT}}dp \end {flalign*}" /></div> <p>For the fraction of molecules with speeds between v and v + dv, substitute p=mv to get</p> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-821994-4"><img src="http://statmech.wikidot.com/local--math/eqs/0575fc094fd5635440cb8f8af71f5ca9.png" alt="f(v)dv=4\pi v^2\left(\frac {m} {2\pi kT}\right)^{\frac 3 2}e^{\frac {-mv^2} {2kT}}dv" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-2975</guid>
				<title>Problem 25</title>
				<link>http://statmech.wikidot.com/forum/t-2975/problem-25</link>
				<description></description>
				<pubDate>Mon, 08 Jan 2007 16:31:46 +0000</pubDate>
				<wikidot:authorName>plumleyj</wikidot:authorName>				<wikidot:authorUserId>4210</wikidot:authorUserId>				<content:encoded>
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						 <p>There are a total of four degrees of freedom in a two dimensional diatomic system</p> <p><img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/4c5a6ce945ceff7c33f162b744fed345.png" alt="q_{vib}" /> is the same as for a three-dimensional diatomic gas;</p> <p><img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/bfa66ceeac397a9d7c0624c663768f7b.png" alt="q_{rot}" /> with a degeneracy of 2 for all J except J=0, for which the degeneracy is 1;</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-484626-1"><img src="http://statmech.wikidot.com/local--math/eqs/9840cadc4557eba97336fc6073c645d6.png" alt="q_{rot} = \sum_j g_j e^{-\beta \varepsilon_j} = e^{-\beta \varepsilon_0} + 2\sum_j e^{-\beta \varepsilon_j} =1+2\sum_j e^{\frac{-\beta\hbar^2 J^2}{ 2I}} = 1 + \displaystyle \int_1^\infty e^{\frac{-\beta\hbar^2 J^2}{ 2I}} dJ \approx \left( \frac{\pi T} {\Theta}_{rot}}\right)^{\frac {1} {2}}" /></div> <p>Since <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/4c5a6ce945ceff7c33f162b744fed345.png" alt="q_{vib}" /> is the same as a three dimensional diatomic gas and the <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/8ce42cba3dbd82da1d6c5d145d128a3e.png" alt="q_{trans}" /> is <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/cd32f5db5fcd53fc39a07cbc191ffdbf.png" alt="\frac {2a^2\pi m k T} {\hbar^2}" /> q(T) becomes</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-484626-2"><img src="http://statmech.wikidot.com/local--math/eqs/9aae943972dd81c481caf73a1fb787f3.png" alt="q(T) = \left(\frac {2a^2\pi m k T} {\hbar^2}\right)\left( \frac{\pi T} {\Theta}_{rot}}\right)^{\frac {1} {2}} \left(\frac {e^{\frac {-\Theta_{vib}} {2T}}} {1-e^{\frac {-\Theta_{vib}} {T}}}}\right)" /></div> <p>The average energy becomes</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-484626-3"><img src="http://statmech.wikidot.com/local--math/eqs/2de4190cb3d5e0659d852c003922934c.png" alt="\langle E \rangle = NkT^2\left(\frac{\partial \ln q(T)} {\partial T}\right)_V= \frac {3RT} {2} + \frac {R\Theta_{vib}} {2} + \frac {R \Theta_{vib}} {e^{\frac {-\Theta_{vib}} {T} -1}}" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-2628</guid>
				<title>Problem 9</title>
				<link>http://statmech.wikidot.com/forum/t-2628/problem-9</link>
				<description></description>
				<pubDate>Thu, 28 Dec 2006 05:57:21 +0000</pubDate>
				<wikidot:authorName>plumleyj</wikidot:authorName>				<wikidot:authorUserId>4210</wikidot:authorUserId>				<content:encoded>
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						 <p>Show for fermions</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-531421-1"><img src="http://statmech.wikidot.com/local--math/eqs/7fe5b16ed8c644b612f8f308e00da0e9.png" alt="pV \geq \frac{\langle N \rangle} {\beta}" /></div> <p>Start with:</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-531421-2"><img src="http://statmech.wikidot.com/local--math/eqs/7457d28be291a4dd93dd4ade4f4be23e.png" alt="pV=\frac {1} {\beta} \sum_k \ln \left[1+\lambda e^{-\beta \varepsilon_k}\right] =\frac {1} {\beta}\displaystyle \int^\infty_0\ln \left[1+\lambda e^{-\beta \varepsilon}\right]d\varepsilon" /></div> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-531421-3"><img src="http://statmech.wikidot.com/local--math/eqs/38bf528a0873a896947b6b3e847cdbe0.png" alt="=\frac {1} {\beta}\lim_{\varepsilon \rightarrow \infty} \left[\frac{dilog(1+\lambda e^{-\beta \varepsilon})} {\beta}-\frac{dilog(1+\lambda)} {\beta} \right]" /></div> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-531421-4"><img src="http://statmech.wikidot.com/local--math/eqs/813a528c5042aca2fec049b2404ca1f0.png" alt="=\frac {-dilog(1+\lambda)}{\beta^2}=\frac{-dilog \left[\left(\frac{1}{1+\lambda}\right)^{-1}\right]}{\beta^2}" /></div> <p>Using the relationship; <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/f80ae114ec9b1184d1114f68c9ccea50.png" alt="dilog(\Theta^{-1})= \frac {\pi^2} {10} - \left[\ln(\Theta)\right]^2" /></p> <span class="equation-number">(5)</span> <div class="math-equation" id="equation-531421-5"><img src="http://statmech.wikidot.com/local--math/eqs/722552dfe1db68bd102719f57ff22066.png" alt="pV=\frac {-1} {\beta^2} \left[\frac {\pi^2}{10}- \left(\ln\frac{1}{1+\lambda}\right)^2\right]=\frac {-1} {\beta^2} \left[\frac {\pi^2}{10}-\left(\ln(1+\lambda)\right)^2\right]" /></div> <p>Also,</p> <span class="equation-number">(6)</span> <div class="math-equation" id="equation-531421-6"><img src="http://statmech.wikidot.com/local--math/eqs/5bc1eba02cab656c87f4c9b5a2ca14bc.png" alt="\langle N \rangle = \sum_k \frac {\lambda e^{-\beta \varepsilon_k}} {1+\lambda e^{-\beta \varepsilon_k}}= \displaystyle \int_0^\infty \frac {\lambda e^{-\beta \varepsilon}} {1+\lambda e^{-\beta \varepsilon}}= \frac {\ln (1+\lambda)} {\beta}" /></div> <p>Rearranging equation 6 and substituting into equation 5 results in</p> <span class="equation-number">(7)</span> <div class="math-equation" id="equation-531421-7"><img src="http://statmech.wikidot.com/local--math/eqs/f4fca8b3517b42550bed20542080ce59.png" alt="pV=\frac {-1} {\beta^2} \left[\frac {\pi^2}{10}-\left(\beta\langle N \rangle\right)^2 \right]" /></div> <p>Rearranging equation 7 results in</p> <span class="equation-number">(8)</span> <div class="math-equation" id="equation-531421-8"><img src="http://statmech.wikidot.com/local--math/eqs/aff9b0172f99b53f70b6cebe10a978fa.png" alt="pV=\frac {-\pi^2}{10 \beta^2}+\langle N \rangle^2" /></div> <p>Substitute equation 8 into equation 1 to get</p> <span class="equation-number">(9)</span> <div class="math-equation" id="equation-531421-9"><img src="http://statmech.wikidot.com/local--math/eqs/b083f53c32acaffac48753f54b83d2a3.png" alt="\langle N \rangle^2 \geq \frac {1} {\beta} \left[\langle N \rangle + \frac {\pi^2} {10\beta}\right]" /></div> <p>which is always true</p> <p>Show for bosons</p> <span class="equation-number">(10)</span> <div class="math-equation" id="equation-531421-10"><img src="http://statmech.wikidot.com/local--math/eqs/ac03177fff831a668f2a1ff4e4c330d1.png" alt="pV \leq \frac{\langle N \rangle} {\beta}" /></div> <p>Using the same methodology as above the following equations are derived</p> <span class="equation-number">(11)</span> <div class="math-equation" id="equation-531421-11"><img src="http://statmech.wikidot.com/local--math/eqs/beff48dd1c6084e6e72382c205db4220.png" alt="\beta^2 pV=\frac {\pi^2} {10} - \left[\ln(1-\lambda)\right]^2" /></div> <span class="equation-number">(12)</span> <div class="math-equation" id="equation-531421-12"><img src="http://statmech.wikidot.com/local--math/eqs/f1ff9b4f3ad5fd74ba932587c1979b44.png" alt="-\beta \langle N \rangle = \ln(1-\lambda)" /></div> <p>Substituting equation 12 into equation 11 results in</p> <span class="equation-number">(13)</span> <div class="math-equation" id="equation-531421-13"><img src="http://statmech.wikidot.com/local--math/eqs/e73922616d546db79026a42495d24dcd.png" alt="pV=\frac {\pi^2} {10\beta^2} - \langle N \rangle^2" /></div> <p>Substituting equation 13 into equation 10 results in</p> <span class="equation-number">(14)</span> <div class="math-equation" id="equation-531421-14"><img src="http://statmech.wikidot.com/local--math/eqs/011905a6f58a27d6969f2944ebea3f58.png" alt="\frac {\pi^2} {10\beta^2} - \langle N \rangle^2 \leq \frac {\langle N \rangle} {\beta}" /></div> <p>Rearranging equation 14 results in</p> <span class="equation-number">(15)</span> <div class="math-equation" id="equation-531421-15"><img src="http://statmech.wikidot.com/local--math/eqs/c9e0b7ff1b2e4b29933a02858624341e.png" alt="\langle N \rangle^2 \geq \frac {1} {\beta} \left[ \frac {\pi^2} {10\beta} -\langle N \rangle\right]" /></div> <p>Which is always true</p> 
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				<guid>http://statmech.wikidot.com/forum/t-2061</guid>
				<title>Problem 11</title>
				<link>http://statmech.wikidot.com/forum/t-2061/problem-11</link>
				<description></description>
				<pubDate>Thu, 07 Dec 2006 21:45:56 +0000</pubDate>
				<wikidot:authorName>juliantalbot</wikidot:authorName>				<wikidot:authorUserId>4149</wikidot:authorUserId>				<content:encoded>
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						 <p>Start from</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-844980-1"><img src="http://statmech.wikidot.com/local--math/eqs/dbbef2590ca7f8b6339cb1e26d47ea02.png" alt="B_2=-\frac{\beta}{6}\int_0^{\infty}r\frac{du}{dr}e^{-\beta u(r)}4\pi r^2 dr" /></div> <p>Substitute <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/5807a2c43161dc8399448c783dec500c.png" alt="u(r)=-\alpha/ r^n,\;\;n&gt;3" /> giving</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-844980-2"><img src="http://statmech.wikidot.com/local--math/eqs/f7863f8e3d169e33bd712718e8d2c7ed.png" alt="B_2=\frac{2\pi n\alpha\beta}{3}\int_0^{\infty}r^{2-n}e^{-\beta\alpha/r^n} dr" /></div> <p>This suggests the gamma function. So let <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/1e143a3fd5f11ebd288b0cf649e4d7cb.png" alt="t=\beta\alpha/ r^n" /> or <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/f7dd46f5572cc09a00a1d815681dea7b.png" alt="r=(\beta\alpha/t)^{1/n}" /><br /> Substituting gives</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-844980-3"><img src="http://statmech.wikidot.com/local--math/eqs/58479b6b5745590dfda348c04f5c42af.png" alt="B_2=\frac{2\pi}{3}(\beta\alpha)^{3/n}\int_0^{\infty}t^{-3/n}e^{-t} dt" /></div> <p>Using the definition of the gamma function finally gives</p> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-844980-4"><img src="http://statmech.wikidot.com/local--math/eqs/adef8d1696d4da1d27c1c2fc8f890605.png" alt="B_2=\frac{2\pi}{3}(\beta\alpha)^{3/n}\Gamma(1-3/n)" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-2043</guid>
				<title>Problem 10</title>
				<link>http://statmech.wikidot.com/forum/t-2043/problem-10</link>
				<description></description>
				<pubDate>Wed, 06 Dec 2006 21:54:35 +0000</pubDate>
				<wikidot:authorName>JT</wikidot:authorName>				<wikidot:authorUserId>4187</wikidot:authorUserId>				<content:encoded>
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						 <p>Start from <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/ec14e2e70ccc6213456bbcf48eb82987.png" alt="B_2(T)=-\frac{1}{2}\int_0^{\infty}(e^{-\beta u(r)}-1)4\pi r^2dr" />. Integrate by parts to get</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-835660-1"><img src="http://statmech.wikidot.com/local--math/eqs/bf1c36b822ee1b6c18d95aeef16202bd.png" alt="B_2(T)=-\frac{2\pi}{3}[r^3(e^{-\beta u(r)}-1)]_0^{\infty}-\frac{\beta}{6}\int_0^{\infty}r\frac{du(r)}{dr}e^{-\beta u(r)}4\pi r^2dr" /></div> <p>If <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/b812c8456d70ba20e6a3401afd9d0297.png" alt="\lim_{r\rightarrow\infty}r^3(e^{-\beta u(r)}-1)=0" /> then</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-835660-2"><img src="http://statmech.wikidot.com/local--math/eqs/c35878af7b757308234e76e72be74ee5.png" alt="B_2(T)=-\frac{\beta}{6}\int_0^{\infty}r\frac{du(r)}{dr}e^{-\beta u(r)}4\pi r^2dr" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-1984</guid>
				<title>Problem 4</title>
				<link>http://statmech.wikidot.com/forum/t-1984/problem-4</link>
				<description></description>
				<pubDate>Mon, 04 Dec 2006 19:10:17 +0000</pubDate>
				<wikidot:authorName>plumleyj</wikidot:authorName>				<wikidot:authorUserId>4210</wikidot:authorUserId>				<content:encoded>
					<![CDATA[
						 <p>Show that</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-690351-1"><img src="http://statmech.wikidot.com/local--math/eqs/e128d6f8723975c544ec391d759f8953.png" alt="p=kT\left(\frac{\partial \ln\Xi} {\partial V}\right)_{\mu,T}=kT\frac {\ln \Xi} {V}" /></div> <p>Utilizing Euler's Theorem;</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-690351-2"><img src="http://statmech.wikidot.com/local--math/eqs/119fb46b9969f627521613e8ecd5d696.png" alt="\ln\Xi\left(\lambda V, T,\mu\right)=\lambda \ln \Xi \left(V,T,\mu\right)" /></div> <p>Take the derivative of both sides with respect to <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/c6a6eb61fd9c6c913da73b3642ca147d.png" alt="\lambda" />;</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-690351-3"><img src="http://statmech.wikidot.com/local--math/eqs/e10ec81d225d8648c5cdeebab73410f0.png" alt="\left(\frac {\partial \ln \Xi} {\partial \lambda V}\right)_{\mu ,T} \frac {\partial \lambda V} {\partial \lambda}= \ln \Xi" /></div> <p>Set <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/c6a6eb61fd9c6c913da73b3642ca147d.png" alt="\lambda" /> equal to 1;</p> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-690351-4"><img src="http://statmech.wikidot.com/local--math/eqs/21d6a4a63db0d0bc9b36ef45bedf39b3.png" alt="\left(\frac {\partial \ln \Xi} {\partial V}\right)_{\mu ,T} V=\ln \Xi" /></div> <p>Rearrange the equation;</p> <span class="equation-number">(5)</span> <div class="math-equation" id="equation-690351-5"><img src="http://statmech.wikidot.com/local--math/eqs/04ab008fa90e31e533aa6a34058b46ff.png" alt="\left(\frac {\partial \ln \Xi} {\partial V}\right)_{\mu ,T}= \frac {\ln \Xi} {V}" /></div> <p>Substitute into equation 1 to get</p> <span class="equation-number">(6)</span> <div class="math-equation" id="equation-690351-6"><img src="http://statmech.wikidot.com/local--math/eqs/c7abf561bebcab65ebca97cbf97563ac.png" alt="p=kT\frac {\ln \Xi} {V}" /></div> 
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				<guid>http://statmech.wikidot.com/forum/t-1844</guid>
				<title>Problem 1</title>
				<link>http://statmech.wikidot.com/forum/t-1844/problem-1</link>
				<description></description>
				<pubDate>Wed, 29 Nov 2006 20:47:33 +0000</pubDate>
				<wikidot:authorName>JT</wikidot:authorName>				<wikidot:authorUserId>4187</wikidot:authorUserId>				<content:encoded>
					<![CDATA[
						 <p>Let z denote the distance fallen so that the height at time t is h - z(t). The equation of motion is</p> <span class="equation-number">(1)</span> <div class="math-equation" id="equation-145662-1"><img src="http://statmech.wikidot.com/local--math/eqs/ec8b4e00751b0cbb1ab45f8a2234e675.png" alt="F=mg-\gamma v=m\frac{d^2z}{dt^2}" /></div> <p>The terminal velocity is attained when the net force on the body is zero. This gives</p> <span class="equation-number">(2)</span> <div class="math-equation" id="equation-145662-2"><img src="http://statmech.wikidot.com/local--math/eqs/471b758ed301283c77339a9cdc0d034d.png" alt="v_{\infty}=\frac{mg}{\gamma}" /></div> <p>To solve the equation of motion we use the result that</p> <span class="equation-number">(3)</span> <div class="math-equation" id="equation-145662-3"><img src="http://statmech.wikidot.com/local--math/eqs/65a79f2d0788b3ae1e20ae7688854940.png" alt="\frac{d^2z}{dt^2}=v\frac{dv}{dz}" /></div> <p>Integrating gives</p> <span class="equation-number">(4)</span> <div class="math-equation" id="equation-145662-4"><img src="http://statmech.wikidot.com/local--math/eqs/9473cfdac06ad0ed7b0770f2621fe366.png" alt="z=-\frac{m^2g}{\gamma^2}\ln(1-v/v_{\infty})" /></div> <p>Integrating again gives</p> <span class="equation-number">(5)</span> <div class="math-equation" id="equation-145662-5"><img src="http://statmech.wikidot.com/local--math/eqs/9b3db27a5b3d5de58f43fb73cd88380a.png" alt="z=\frac{m^2g}{\gamma^2}\ln(\exp(\frac{\gamma}{m}t)+1)" /></div> <p>For large t, this gives <img class="math-inline" src="http://statmech.wikidot.com/local--math/inline/f33ac2c0c38dff5735f7d5ab13db75b3.png" alt="z=v_{\infty}t" /></p> 
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