Some Random HR Diagram Questions

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tyguy

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The following are a few questions I was left to ponder after astronomy class. I want to make it discernible that I am not throwing up homework questions because im too lazy to read <img src="/images/icons/smile.gif" /><br /><br />Anyhow, any help would be very appreciated.<br /><br />Firstly, suppose a cluster of stars formed 10 million years ago. Assuming we can see ALL the stars..would you expect the HR diagram of the cluster to show stars on the very high mass end of the main sequence or the very low, and how come?<br /><br />Second, lets say the suns material were re-dispersed into space at a density of 10 atoms/cm3...how big of a cloud would it make?<br /><br />This one I really have no idea how to find the answer. Ive gotten as far as finding that the sun contains about 10 to the 57th atoms. Anyone who can help with this one gets 4 gold stars <img src="/images/icons/smile.gif" /><br /><br />Thanks
 
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origin

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Come on Ty!<br /><br />You have a density (10 atoms/cm3)<br />You have a mass (10^57 atoms)<br /><br />You need to find the volume. So find the volume!!!<br /> <div class="Discussion_UserSignature"> </div>
 
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tyguy

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Well, I have V=4/3 X 3.14^3...but is this the right equation for a sphere?<br /><br />Or is it simple and im just dumb?
 
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nimbus

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You can find the equation for a sphere's volume anywhere.<br />Like origin said, the answer you want is right under your nose <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>
 
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tyguy

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Right, but is it as simple as dividing mass by density or do I need to incorporate the above equation?
 
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origin

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When I was in the Navy if you answered a question not asked on a test you would see RTFQ written across the answer. The first word is read and the last word is question.<br /><br />So I say RTFQ!<br /><br />I see nothing about the shape the 'cloud' would take in the question.<br /><br />Good luck.<br /><br /> <div class="Discussion_UserSignature"> </div>
 
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tyguy

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Its more "compare the cloud with the size of the solar system"<br /><br />I mean, im just not sure of the equation, nothing is going to change by re-reading the question.
 
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origin

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What <b>exactly</b> is the question?<br /><br />Scientific type people are real sticklers. You have to be very specific about units, definitions and questions.<br /><br /> <div class="Discussion_UserSignature"> </div>
 
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tyguy

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"If the Sun's material were re-dispersed into space at a density of 10 atoms/cm^3, typical of some interstellar clouds, how big a cloud would it make? (Hint: the Sun contains about 10^57 atoms. 1 pc = 3 10^18 cm =2 10^5 AU)"
 
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origin

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The question says nothing about a sphere, cube or a parabaloid!<br /><br />Just how big. Yes it is that easy, don't make the question harder than it is. (hint: RTFQ)<br /><br />RTFQ - has saved me many many times, I am not being condescending! This is an acronym to live by!<br /><br />Edited to add; After I RTFQ again I see your confusion. Why give you the size of a pc if they were not interested in the distance across the cloud. Sooo, I probably would use a sphere stating that "assuming the cloud was a sphere yada, yada.<br /><br />Poorly worded question if you ask me!<br /><br /> <div class="Discussion_UserSignature"> </div>
 
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tyguy

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The reason I mentioned a sphere was I thought I had to get the density of the sun using the density-sphere equation, but I guess not.<br /><br />I appreciate your help but reading TF Question isnt getting me any closer :/
 
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MeteorWayne

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Right, and this isn't homework <img src="/images/icons/rolleyes.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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Mee_n_Mac

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<font color="yellow">"If the Sun's material were re-dispersed into space at a density of 10 atoms/cm^3, typical of some interstellar clouds, how big a cloud would it make? (Hint: the Sun contains about 10^57 atoms. 1 pc = 3 10^18 cm =2 10^5 AU)"</font><br /><br />Seems to me the only unambiguous answer for "big" is to give a volume. No matter what the shape of the cloud, it would, assuming a uniform density, have only 1 volume. If after saying the answer is X cm^3, you want to add that this <b>could</b> be a sphere of radius R (assuming a spherical cloud), then by all means add it. But give the volume first.<br /><br /> <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>
 
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