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			<title>Can I share an AC neutral w/ two different voltage requirements?</title>
			<link>http://www.physicsforums.com/showthread.php?t=606562&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 21:22:38 GMT</pubDate>
			<description>I have a situation on a dashboard where the dashboard itself (metal) is the “ground” and two different items require a different voltage.  One item requires 5 volts and the other requires 25-28...</description>
			<content:encoded><![CDATA[<div>I have a situation on a dashboard where the dashboard itself (metal) is the “ground” and two different items require a different voltage.  One item requires 5 volts and the other requires 25-28 volts.  Each of these items has a single lead.  How can I attach two different ac power supplies when there is a shared neutral/ground?</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=102">Electrical Engineering</category>
			<dc:creator>tuntavern</dc:creator>
			<guid isPermaLink="true">http://www.physicsforums.com/showthread.php?t=606562</guid>
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			<title>Hand Grenade in Solar Orbit</title>
			<link>http://www.physicsforums.com/showthread.php?t=606561&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 21:17:31 GMT</pubDate>
			<description><![CDATA[Hi, folks.  I'm new here and came looking for some expert input on this odd question that came up as a friend and I were considering a hypothetical. 
 
Suppose a hand grenade were orbiting the...]]></description>
			<content:encoded><![CDATA[<div>Hi, folks.  I'm new here and came looking for some expert input on this odd question that came up as a friend and I were considering a hypothetical.<br />
<br />
Suppose a hand grenade were orbiting the sun---say, half way between the orbits of Mars and Jupiter.  And to make things easy, suppose that  the grenade orbiting in the same direction as these other planets, and at a speed generally consistent with that of planetary orbits. <br />
<br />
What happens to the shrapnel if the grenade explodes?  After a time, will we find a large field of scattered shrapnel all moving in the original direction and speed?  Will some shrapnel end up on an opposite course from the original course?  Will any shrapnel end up  orbiting on a different plane than the original (pre-explosion) plane?  Will some shrapnel leave the solar system?  I realize these are only a few possible results.<br />
<br />
If anyone can chime in with an answer, I'd sure appreciate it.  And if a consensus can be reached, that's even better!<br />
<br />
Thanks!</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=68">Astrophysics</category>
			<dc:creator>jackpelham</dc:creator>
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			<title><![CDATA[What does this example say about the applicability of Bell's inequalities?]]></title>
			<link>http://www.physicsforums.com/showthread.php?t=606560&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 21:12:22 GMT</pubDate>
			<description><![CDATA[It is commonly believed that Bell's inequalities are a theoretical derivation of a condition that *must* be satisfied by locally causal theories.  Therefore, it is often concluded that violation of...]]></description>
			<content:encoded><![CDATA[<div>It is commonly believed that Bell's inequalities are a theoretical derivation of a condition that <b>must</b> be satisfied by locally causal theories.  Therefore, it is often concluded that violation of these inequalities by experiments provides very strong evidence (if not conclusive proof, the only doubt being due to imperfect experiments) that reality is non-local. <br />
<br />
However, I present a macroscopic example using coins where, Bell's theorem is always violated in the experiments. I would like to stimulate discussion of <br />
<br />
1) why this specific example exhibits such behaviour?<br />
2) where is the non-locality, or non-reality, or any other spooky conclusion?<br />
3) what does this mean for the popular belief that Bell's inequalities are applicable to the EPRB experimental results?<br />
<br />
Here it goes:<br />
<br />
We have three coins labelled &quot;a&quot;, &quot;b&quot;, &quot;c&quot;, if we toss all three a very large number of times, it follows that the inequality |ab + ac| - bc &lt;= 1 will never be violated for any individual case and therefore for averages |&lt;ab&gt; + &lt;ac&gt;| - &lt;bc&gt; &lt;= 1 will also never be violated (where  heads = +1 &amp; tails = -1).<br />
<br />
<b>Proof</b>: For three coins with outcomes ±1, there are 8 possibilities. the LHS for each possibility is always &lt;=1 as illustrated below:<br />
a,b,c = (+1,+1,+1): |(+1) + (+1)| - (+1) &lt;= 1, obeyed<br />
a,b,c = (+1,+1,-1): |(+1) + (-1)| - (-1) &lt;= 1, obeyed<br />
a,b,c = (+1,-1,+1): |(-1) + (+1)| - (-1) &lt;= 1, obeyed<br />
a,b,c = (+1,-1,-1): |(-1) + (-1)| - (+1) &lt;= 1, obeyed<br />
a,b,c = (-1,+1,+1): |(-1) + (-1)| - (+1) &lt;= 1, obeyed<br />
a,b,c = (-1,+1,-1): |(-1) + (+1)| - (-1) &lt;= 1, obeyed<br />
a,b,c = (-1,-1,+1): |(+1) + (-1)| - (-1) &lt;= 1, obeyed<br />
a,b,c = (-1,-1,-1): |(+1) + (+1)| - (+1) &lt;= 1, obeyed<br />
<br />
<b>The Bell inequality Challenge</b>:<br />
Find a locally realistic situation which violates the above inequality. According to Bell and proponents, this is impossible to do.<br />
<br />
<b>Experimental Violation</b>:<br />
We have 3 coins labeled &quot;a&quot;,&quot;b&quot;,&quot;c&quot;, inside a special box. A button on the box releases only two of the coins at random when pressed. The coins must be returned to the box before the next press, therefore only two of the three coins can ever be outside of the box at the same time.<br />
<br />
Since we can not toss all three at once, and since the inequality only contains averages of pairs of outcomes, we assume the inability to measure all three simultaneously is inconsequential. We decide to perform the experiment by tossing just the pairs a very large number of times and group the results into 3 runs for the pairs (a,b), (a,c), (b,c) tosses. Using the pairs, we calculate &lt;ab&gt;, &lt;ac&gt; and &lt;bc&gt;. Even though the data for each pair appears random, we find that from our data &lt;ab&gt; = -1, &lt;ac&gt; = -1 and &lt;bc&gt; = -1, which violates the inequality when substituted into the LHS. (i.e 3 &lt;= 1 according to the inequality).  This was supposed to be impossible according to the challenge!!! Does this mean &quot;local causality&quot; or realism is false?<br />
<br />
<b>The Explanation</b>:<br />
Consider the following: Each coin has a programmable bias which can be changed by the box just before it is released but not after. The box has an internal clock which keeps track of the time (t) in seconds. The above scenario [&lt;ab&gt; = -1, &lt;ac&gt; = -1 and &lt;bc&gt; = -1 ] can then easily be realized if the special box operates as follows:<br />
<br />
Every time a button is pressed, calculate calculate sin(t) where t is the time read off the internal clock. If sin(t) &gt; 0, program coin &quot;a&quot; to be biased for heads (+1) and coin &quot;c&quot; to be biased for tails (-1). Then randomly pick two of the three coins. If coin &quot;b&quot; is one of the picks, program coin &quot;b&quot; to be biased for tails (-1) if the other pick is coin &quot;a&quot;, otherwise program coin &quot;b&quot; to be biased for heads (-1). If sin(t) &lt;= 0 reverse all the signs.<br />
<br />
<b>Conclusion</b>:<br />
a) The box will always produce &lt;ab&gt; = -1, &lt;ac&gt; = -1 and &lt;bc&gt; = -1, no matter how many times the coins are tossed, (1 or 50 billion).<br />
b) The results will be random<br />
c) The inequality will always be violated no matter how many times the coins are tossed (1 or 50 billion)<br />
d) The box and coins operate in a completely locally causal manner. <br />
e) The result of each toss is non-contextual and predetermined from the moment the coins are produced<br />
f) There are no loopholes in the experiment<br />
f) There is no spooky business happening<br />
g) YET Bell's inequality is violated.<br />
<br />
<br />
How come?</div>

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			<category domain="http://www.physicsforums.com/forumdisplay.php?f=62">Quantum Physics</category>
			<dc:creator>billschnieder</dc:creator>
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			<title>Digital Signal Processing</title>
			<link>http://www.physicsforums.com/showthread.php?t=606557&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:52:27 GMT</pubDate>
			<description>I have a couple of questions about the theory about how to tell whether a system is casual and FIR or IIR. 
 
First point is about a casual system. Is it true that all FIR systems are casual? How can...</description>
			<content:encoded><![CDATA[<div>I have a couple of questions about the theory about how to tell whether a system is casual and FIR or IIR.<br />
<br />
First point is about a casual system. Is it true that all FIR systems are casual? How can you tell if an IIR system is casual?<br />
<br />
I am I correct in thinking that a FIR system only has a numerator and IIR system has both a numerator and denominator?<br />
<br />
For example: h(n) = u(n+1) -u(n-1) and h(n) = 5^n . U(-n) <br />
<br />
Are both of these FIR systems?</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=102">Electrical Engineering</category>
			<dc:creator>cf9219</dc:creator>
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			<title>Mac/PC users: processing power affected by battery power?</title>
			<link>http://www.physicsforums.com/showthread.php?t=606556&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:45:20 GMT</pubDate>
			<description><![CDATA[Has anyone heard of a feature whereby display processing power is linked to system power levels ?eg.: if you're operating on battery rather than wall plug, can that have an effect on whether you get...]]></description>
			<content:encoded><![CDATA[<div>Has anyone heard of a feature whereby display processing power is linked to system power levels ?eg.: if you're operating on battery rather than wall plug, can that have an effect on whether you get full acceleration when watching videos?<br />
<br />
My sister claims that, on her Mac, when the battery is running low, the video will not be as smooth (choppy, audio cut-outs). <br />
<br />
I think this is complete nonsense, but it's occurred to me that it is not <i>totally</i> impossible that a computer system might disable some high-performance features such as video acceleration in an effort to conserve battery power.<br />
<br />
Anyone ever heard of the such a thing?</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=190">Computers</category>
			<dc:creator>DaveC426913</dc:creator>
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			<title>Compressed Sensing References</title>
			<link>http://www.physicsforums.com/showthread.php?t=606555&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:34:16 GMT</pubDate>
			<description><![CDATA[Not sure if this is best subforum for this ... but what I'm looking for is some recommendations for books/articles containing a nice introduction to compressed sensing. 
 
I'm not a mathematician...]]></description>
			<content:encoded><![CDATA[<div>Not sure if this is best subforum for this ... but what I'm looking for is some recommendations for books/articles containing a nice introduction to compressed sensing.<br />
<br />
I'm not a mathematician although I would like to think I'm relatively mathematically sophisticated.  I appreciate proofs in the right places, but what I really want is something with a lot of motivation/intuition along with the formal stuff.  But I also don't want something too pedestrian.  I have plenty of time so I'm open to background stuff as well.<br />
<br />
Any suggestions?</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=78">Set Theory, Logic, Probability, Statistics</category>
			<dc:creator>Physics Monkey</dc:creator>
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			<title>Gaydar?</title>
			<link>http://www.physicsforums.com/showthread.php?t=606554&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:33:24 GMT</pubDate>
			<description>---Quote--- 
A study found that students asked to tell whether someone was gay or straight guessed correctly more often than could be put down to mere chance. 
Women had greater accuracy with 65 per...</description>
			<content:encoded><![CDATA[<div><div style="margin:20px; margin-top:5px; ">
	<div class="smallfont" style="margin-bottom:2px">Quote:</div>
	<table cellpadding="6" cellspacing="0" border="0" width="100%">
	<tr>
		<td class="alt2">
			<hr />
			
				A study found that students asked to tell whether someone was gay or straight guessed correctly more often than could be put down to mere chance.<br />
Women had greater accuracy with 65 per cent able to identify someone's sexuality at a glance, while men were correct 57 per cent of the time.<br />
Evidence suggest it is easier to recognise gay women's faces than men's even when photos were shown upside down and with no hairstyle visible.<br />
Researchers in journal PLoS One say the results suggest we may unconsciously make gay or straight decisions when meeting a new face.<br />
Joshua Tabak, of the University of Washington, said: &quot;It may be similar to how we don't have to think about whether someone is a man or a woman or black or white.
			
			<hr />
		</td>
	</tr>
	</table>
</div><a href="http://www.telegraph.co.uk/science/science-news/9269298/Women-really-do-have-a-gaydar.html" target="_blank">http://www.telegraph.co.uk/science/s...-a-gaydar.html</a><br />
<br />
My question: what photos were shown, and do they demonstrate a confirmation bias in selecting only masculine looking women as the lesbian examples? <br />
<br />
A couple weeks ago I was going through my pictures trying to put together an album of the lesbians I have photographed in preparation for a possible show of these pics at a coffeehouse in a neighborhood known for its larger gay population. I found I had to avoid selecting shots that happened to enhance more masculine aspects of them. That is, I started off unconsciously selecting the most masculine looking shots. <br />
<br />
If I put together an album of those masculine looking shots and then added a bunch of random, very feminine looking shots of women I know not to be lesbians, I could easily stack the deck such that almost anyone would be able to pick out the lesbians. Is this what happened in this study? <br />
<br />
My own &quot;gaydar&quot; is highly dependent on hearing how someone talks, how they dress and their hair, and how they move. It's only about 50% accurate, too, in that some people make a point of telegraphing their sexuality and others completely avoid it. Unless they &quot;stacked the deck&quot; as I suggested, I very much doubt it's possible to tell if someone's gay from the shape of their face alone and in a still photograph.</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=199">Relationships</category>
			<dc:creator>zoobyshoe</dc:creator>
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			<title>gnuplot: ylabels + ytics + LaTeX causes too much whitespace</title>
			<link>http://www.physicsforums.com/showthread.php?t=606553&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:31:45 GMT</pubDate>
			<description><![CDATA[I'm hoping someone can help me with the following problem. I have a .p file for generating a .eps file using gnuplot. I want both the y-axis label and the y-axis tics to be formatted using LaTeX....]]></description>
			<content:encoded><![CDATA[<div>I'm hoping someone can help me with the following problem. I have a .p file for generating a .eps file using gnuplot. I want both the y-axis label and the y-axis tics to be formatted using LaTeX. Getting this done is no problem. The problem I am having is that having both of these options creates an unreasonable amount of white-space between the label and tics, which squashes the actual plot. Setting the offset for either the y label or the tics just moves them; the plot does not resize itself accordingly. Does anyone know how to fix this issue?<br />
<br />
My .p file is<br />
<br />
<div style="margin:20px; margin-top:5px">
	<div class="smallfont" style="margin-bottom:2px">Code:</div>
	<hr /><code style="margin:0px" dir="ltr" style="text-align:left">reset<br />
set term epslatex standalone size 5 in, 3 in color colortext # 5 in, 3 in is default<br />
set output &quot;output.tex&quot;<br />
<br />
#set autoscale<br />
set xrange [0:11]<br />
set yrange [0:pi]<br />
set key right bottom<br />
set key spacing 1.3<br />
set xtics 0,1,10<br />
set ytics ('$0$' 0, '$\frac{\pi}{12}$' pi/12, '$\frac{\pi}{6}$' pi/6, '$\frac{\pi}{4}$' pi/4, '$\frac{\pi}{3}$' pi/3, '$\frac{5\pi}{12}$' 5*pi/12,&nbsp; '$\frac{\pi}{2}$' pi/2, '$\frac{7\pi}{12}$' 7*pi/12, '$\frac{2\pi}{3}$' 2*pi/3, '$\frac{3\pi}{4}$' 3*pi/4)<br />
set style line 1 lt 1 lw 9 pt 0 ps 0<br />
set style line 2 lt 3 lw 9 pt 0 ps 0<br />
set xlabel 'Frequency $\omega$' #offset 0.0,0.5<br />
set ylabel 'Phase $\varphi$' #offset 15,0.0<br />
plot 'phasevomega.txt' u 1:(atan2($4,$3)) every ::(47*384)::(48*384-1) w lines ls 1 lc rgb&quot;red&quot; title 'Simulation data'<br />
<br />
set output</code><hr />
</div>Thanks for any suggestions.</div>

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			<category domain="http://www.physicsforums.com/forumdisplay.php?f=189"><![CDATA[Math & Science Software]]></category>
			<dc:creator>Mute</dc:creator>
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			<title>Electron spin and the Pauli Exclusion Principle.</title>
			<link>http://www.physicsforums.com/showthread.php?t=606551&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:17:14 GMT</pubDate>
			<description>How is it that only 1 spin up and 1 spin down electron are allowed in an atom even though there is no measurement to collapse the state function?</description>
			<content:encoded><![CDATA[<div>How is it that only 1 spin up and 1 spin down electron are allowed in an atom even though there is no measurement to collapse the state function?</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=62">Quantum Physics</category>
			<dc:creator>Jimmy Snyder</dc:creator>
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			<title>Calculating total price using kilo watt hours?</title>
			<link>http://www.physicsforums.com/showthread.php?t=606550&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:17:08 GMT</pubDate>
			<description>What is the cost for 1 hr? 
 
Current = 1 A 
Voltage = 25 000 V 
Kilowatt hour = £0.10 KWhr</description>
			<content:encoded><![CDATA[<div>What is the cost for 1 hr?<br />
<br />
Current = 1 A<br />
Voltage = 25 000 V<br />
Kilowatt hour = £0.10 KWhr</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=111">General Physics</category>
			<dc:creator>j-lee00</dc:creator>
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			<title><![CDATA[How to use Matlab ODE solver "events" to stop an integration]]></title>
			<link>http://www.physicsforums.com/showthread.php?t=606549&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:16:58 GMT</pubDate>
			<description><![CDATA[I'm using Matlab's ODE solver (specifically ode15s) to solve a system of equations. The sum of the values of the equations eventually arrive at a steady state, but the time at which that occurs is...]]></description>
			<content:encoded><![CDATA[<div>I'm using Matlab's ODE solver (specifically ode15s) to solve a system of equations. The sum of the values of the equations eventually arrive at a steady state, but the time at which that occurs is dependent on several things, not known beforehand, and is one of the things I'm studying.<br />
<br />
Consequently, I'd like to set tf in the call to the ODE solver to a value that I'm confident is beyond that time, and cause the integration to stop once a certain convergence criteria is met. <br />
<br />
I have been unable to use 'Events' to do this effectively. Here is the function that is called by 'Events': <br />
<br />
function [value,isterminal,direction] = Tprime_converger(t,T)<br />
<br />
if length(t) == 1  %convergence can only be checked for t&gt;1<br />
value = 1;<br />
else<br />
value = abs(sum(T(length(t)-1,;)) - sum(T(length(t),;))) - 2*eps;<br />
end<br />
<br />
isterminal = 1;<br />
direction = 0;<br />
<br />
end<br />
<br />
<br />
Any help would be greatly appreciated.<br />
<br />
Thanks.<br />
-ryan</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=189"><![CDATA[Math & Science Software]]></category>
			<dc:creator>ryan.j</dc:creator>
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			<title>Learning Elementary Fourier Analysis</title>
			<link>http://www.physicsforums.com/showthread.php?t=606548&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:12:57 GMT</pubDate>
			<description><![CDATA[Hey guys, 
 
Is it possible to learn, (at least) elementary fourier analysis, after completing Spivak's "Calculus"?. If not, what more is there to learn before one can begin fourier analysis?]]></description>
			<content:encoded><![CDATA[<div>Hey guys,<br />
<br />
Is it possible to learn, (at least) elementary fourier analysis, after completing Spivak's &quot;Calculus&quot;?. If not, what more is there to learn before one can begin fourier analysis?</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=21">Science Book Discussion</category>
			<dc:creator>GoutamTmv</dc:creator>
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			<title><![CDATA[what happened to our "Belief in Aliens" thread??]]></title>
			<link>http://www.physicsforums.com/showthread.php?t=606547&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:10:58 GMT</pubDate>
			<description><![CDATA[i just got a warning about it (i guess i should be grateful it's not an infraction), but when i wanted to review the whole thing (you know... who said what), it disappeard.]]></description>
			<content:encoded><![CDATA[<div>i just got a warning about it (i guess i should be grateful it's not an infraction), but when i wanted to review the whole thing (you know... who said what), it disappeard.</div>

]]></content:encoded>
			<category domain="http://www.physicsforums.com/forumdisplay.php?f=19"><![CDATA[Forum Feedback & Announcements]]></category>
			<dc:creator>rbj</dc:creator>
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			<title>Compton scattering problem - how much did wavelength change by?</title>
			<link>http://www.physicsforums.com/showthread.php?t=606546&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 20:10:42 GMT</pubDate>
			<description>*1. The problem statement, all variables and given/known data* 
 
How much will the wavelength of the incident X-ray photon change by if it is scattered by 30 degrees when it interacts with an...</description>
			<content:encoded><![CDATA[<div><b>1. The problem statement, all variables and given/known data</b><br />
<br />
How much will the wavelength of the incident X-ray photon change by if it is scattered by 30 degrees when it interacts with an electron?<br />
<br />
<b>2. Relevant equations</b><br />
<br />
This is Compton scattering.<br />
<br />
This is the equation I used:<br />
<br />
lambda ' - lambda (0) = (h)/(m(e)c) (1-cos theta)<br />
<br />
where h is planck's constant, me is the mass of the electron, c is speed of light.<br />
<br />
<b>3. The attempt at a solution</b><br />
<br />
Basically I just subbed in everything into the equation above, and got 2.424 x 10^-12 m.<br />
<br />
The thing I'm not sure about is whether I'm finished or not.<br />
<br />
Does lambda ' minus lambda (0) give me the difference? Did I use the right form of the equation here? Do I need to do anything else?<br />
<br />
Thank you :)</div>

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			<category domain="http://www.physicsforums.com/forumdisplay.php?f=153">Introductory Physics</category>
			<dc:creator>daleklama</dc:creator>
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			<title>Problem with NDSOLVE in Mathematica</title>
			<link>http://www.physicsforums.com/showthread.php?t=606542&amp;goto=newpost</link>
			<pubDate>Wed, 16 May 2012 19:46:58 GMT</pubDate>
			<description><![CDATA[Mathematica says: 
 
"NDSolve::alliv: "The function x[t] was specified without dependence on all the independent variables. Each function must depend on all the independent variables."" 
 
But...]]></description>
			<content:encoded><![CDATA[<div>Mathematica says:<br />
<br />
&quot;NDSolve::alliv: &quot;The function x[t] was specified without dependence on all the independent variables. Each function must depend on all the independent variables.&quot;&quot;<br />
<br />
But function x depends only on t, there is no other variable specified in the code. <br />
<br />
What could be the problem? I attach .nb file below.</div>


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	<td><a href="http://www.physicsforums.com/attachment.php?attachmentid=47353&amp;d=1337197589">Untitled-2.nb</a> (3.7 KB)</td>
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			<dc:creator>nikolafmf</dc:creator>
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