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Old Nov 14th 2015, 09:32 AM   #21
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Sorry, yes that includes the casting, but I missed the piston in last night's rush.


Upward force = 44180N

Downward force piston + atm = 2256N + 44765N = 47021N

Add casting = 1000 x 9.81 = 9810N

Total downward force = 47021N + 9810 = 56831N
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Old Nov 16th 2015, 07:58 AM   #22
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Any pointers for part 3?
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Old Nov 16th 2015, 09:34 AM   #23
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help

anyone...

does 1 N/m^2 = 1 Newton ??
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Old Nov 16th 2015, 09:42 AM   #24
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N/m squared is pressure it = 1 Pa
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Old Nov 16th 2015, 10:01 AM   #25
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Any pointers for part 3?
That is why I said you need Cp and Cv.

The steam raises the temperature at constant volume from point 1 (the start) to point 2(the start of lifting) on your PV diagram.

Then the steam continues to raise the temperature at constant pressure to point 3, when the steam is turned off.

So you need to calculate the temperature rises for each part using the appropriate equation of state.
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Old Nov 16th 2015, 10:23 AM   #26
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Ended up figuring that out but not sure how to work put the heat transfer when the piston returns back down?
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Old Nov 16th 2015, 11:46 AM   #27
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Ended up figuring that out but not sure how to work put the heat transfer when the piston returns back down?
So far I've done most of the work here, (post7) so how about describing your version of the next stage on the PV diagram.
That is from point 3 to point 4 using what you have learned in going from point 1 to point 2 to point 3.

We can work on then that.
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Old Nov 16th 2015, 01:22 PM   #28
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Does anyone have a full solution to this problem, would make it a lot easier to understand if i could see it in full, thanks!
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Old Nov 16th 2015, 02:07 PM   #29
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Originally Posted by studiot View Post
So far I've done most of the work here, (post7) so how about describing your version of the next stage on the PV diagram.
That is from point 3 to point 4 using what you have learned in going from point 1 to point 2 to point 3.

We can work on then that.
I don't really know how you think you have done most of the work. I asked for feedback on my answers and you never offered any help. And what you provided us with downards force = upwards force still gave us the pressure that we had.

I've actually gone and done most of the work with friends to try and figure out what's happening. I was only confused with the work done. Like why would I choose the equation "p deltav" instead of m r (t2-t2)

Last edited by Molyticus; Nov 16th 2015 at 02:09 PM.
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Old Nov 19th 2015, 10:34 AM   #30
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Hi, everybody...

I guess this about over. I'm sorry I did not have time to help. But I followed your numbers.
A p-v diagram is needed. I attached mine.

I haven't solved it. Only the "first part." See it here.

http://www.thermospokenhere.com/wp/0..._elevator.html

This is a tedious little problem. Could be worded better.
Good Luck, You Guys, Jim
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Heat powered elevator-p_v_air.png  
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