boles is such a cock head

but he knows his shit, so i guess he gets to do that

9/14/2005 3:23:12 PM

So, no formulas?

9/14/2005 3:31:56 PM

ahaha it sucks for people that saw the sign and left
"no makeup"

9/14/2005 7:31:23 PM

you had a test at night?

9/14/2005 7:50:52 PM

regular class time

9/14/2005 8:05:21 PM

what sign are you talking about

9/14/2005 8:06:23 PM

the one that said mae 301 test cancelled that was taped to the door

9/14/2005 8:15:29 PM

hahaha

9/14/2005 8:19:26 PM

that sucks

9/14/2005 8:20:22 PM

I saw that sign and had to think "is this for real..?"

I saw the two guys who walked out earlier walk back in about 5-10 mins later

I wonder who had the nerve to put that crap up there tho.

9/14/2005 8:28:59 PM

i wonder if there was another 301 class in that room earlier that actaully did have a test cancelled

9/14/2005 8:50:20 PM

Let me get this straight...
So there was a sign that said "MAE test cancelled" when in fact it wasnt, and there is no makeup?

9/14/2005 10:15:15 PM

correct

sign said:

MAE 301 test cancelled
be prepared monday

i just sat down and studied

9/14/2005 11:47:29 PM

Yeah, I think there were a couple of guys that may have not made it back in. I almost didn't stick around, but I figured what's another 10 min to know for sure one way or another.

9/15/2005 12:03:46 AM

so how do you do this ch 4 stuff? i'm skerred

9/19/2005 6:27:45 PM

i dont know the assignment

9/19/2005 6:36:22 PM

If I knew what the questions were, I'd be able to help...

It's not that hard tho

9/19/2005 6:47:33 PM

if it was in an email i missed it

if it was in class well i missed it too

9/19/2005 7:10:05 PM

4.6, 9, 12, 22, 36, 38, 41

9/19/2005 7:21:37 PM

can anybody help me get started with how to do 6?

9/20/2005 2:54:29 PM

^ damn dude!

v= specific volume
V= volume

ok, for 6 you have to find the v for the piston at the stop. draw it out on a P-v for stage 1, 2, 3: at 1.0MPa and 400C, 1.0MPa and 250C, and 500kPa, respectively. now using the table you have to determine if state 2 and 3 has reach the stop or not. if it didn't, the pressure is constant and you can use the constant pressure equation for work. if not, then the pressure would decrease linearly, and you would have to find the area underneath the curve. use the v for state 1, 2, and 3 for the base and 1.0MPa and 500kPa as the height for the area. and you can find the temperature using the table.

[Edited on September 20, 2005 at 5:24 PM. Reason : state, not stage.]

9/20/2005 5:23:36 PM

yea i missed that lecture and i was getting some weird stuff. thanks though

i got everything but 41. if you guys need any help, let me know. anybody have any tips on 41?

9/21/2005 11:04:37 AM

i was wondering about 38 and 41

9/21/2005 11:06:46 AM

I need help please

9/21/2005 12:18:46 PM

38

part a - you have your initial temp and pressure - find your inital v and u from that (tables)
then use your m=v/v equation to find your mass.
then use that mass to find your v2 (with 06.m^3 instead of 0.5)

Now you can work on your final state values. Use the v2 and p2 to find your temp.

part b - Workdone = (P1+ P2)/2 * (v2-v1). You are given all of these values, so even if you can't get part a, you should be able to do this.

part c - Qin = m(u2-u1) + workdone

M and u1 comes from your answers in part one. Workdone is from part B. U2 can be found using the same method you did in part one with using the pressure and v2 values (doing that nasty calculations crap).

Hope that helps. Getting nowhere on 41.

9/21/2005 12:33:49 PM

for 41, find v and V for tank A and B, and volume does not change assume the tank is rigid. when the tanks are mixed together, the specific internal engergy (u) will be the same for both tanks. so draw the P-v diagram for the initial and final state. find the u for the initial and find the u for the final. since the final stage of both tanks are the same, just find the difference in internal energy by final minus initial for both tanks.

hint: the quality for final state is lower than 0.5.

9/21/2005 2:24:01 PM

Is it just me or did everyone get -4 points for not proving that test problem 3 was an ideal gas?

9/21/2005 3:10:33 PM

yeah pretty much

9/21/2005 3:27:01 PM

yea me too
i'm gonna fail

9/21/2005 3:30:36 PM

Screw MAE 301....you'll never use that crap once you graduate.

9/21/2005 9:42:51 PM

well one test three, i got correct final answers for all four questions and ended up with a 79. Why the fuck does it matter if i draw a simple little picture for such a basic energy question. I also lost ten points on my own forgeting to draw the isotherms.

9/21/2005 10:09:03 PM

alright next homework - i got all of them but the first and last one. I think i might be able to figure out the first one though. last one, im having some pretty good trouble.

any help?

9/26/2005 2:37:25 PM

Quote :

"well one test three, i got correct final answers for all four questions and ended up with a 79. Why the fuck does it matter if i draw a simple little picture for such a basic energy question. I also lost ten points on my own forgeting to draw the isotherms."

shit like that will keep you from making mistakes in future classes

everything that boles makes you do: diagrams, units, etc. is all for a reason

they are checks

if the diagram doesnt look right then why?

if the units dont work why?

helped me get an A on my 302 test

9/26/2005 3:20:33 PM

i got the first one
there's an example just like it in our notes pretty much for a
for b you just use Cavg
for c you use the C at room temp which is 300K

just look in the tables they tell you

9/26/2005 8:39:05 PM

Some questions on hw #5
for number 57:
does the W_resistor=deltaU?

number 68:
does the energy balance look like this:
-60-(W_bound+W_elec)=C_v*deltaT
where W_bound=P*deltaV (constant pressure)??

9/26/2005 11:00:41 PM

57, W_resister = deltaH

and you mean, 65. -60-(W_bound+W_elec)=m*C_v*deltaT, and W_bound=P_constant*deltaV

9/27/2005 3:36:10 PM

Yea I was having trouble on both of these because I was forgetting that the specific heats are in terms of unit mass. Well played units..

9/27/2005 4:21:10 PM

anyone know how to do 67??

9/27/2005 11:09:32 PM

I'm stuck on 67 too
I'm using the eqn from the notes Wb=[mR(T2-T1)]/1-n

so I was trying to find T2 and I keep getting 150K
which does not give you 54.8


I also need help on the last one

[Edited on September 27, 2005 at 11:47 PM. Reason : lkj]

9/27/2005 11:46:10 PM

ok for 51. I keep getting 448.58 for part a. I'm using table a-18 for the h values right?

for 67

T2 = P2/p1 * v2/v1 * T1; Are you getting 2462 kPa for P2?

9/27/2005 11:49:56 PM

for 51(a) you need to use table A2(c)

the equation at the top...cbar(p) = a + bT + cT^2 + dT^3 has to be used

so delta_hbar = integral[cbar(p)] = integral[a + bT + cT^2 + dT^3] from T1 to T2

plug in your a, b , c , d values from table A2(c) for nitrogen, then integrate and evaluate from 600 to 1000 K

after that is done you have delta_hbar which you must divide by the molar mass of nitrogen to get delta h.

that wasnt that great of an explanation i know so i'll try to summarize.

look at table A2(c) and plug in the numbers for a , b , c , d and integrate the equation for cbar(p) and evaluate from T1 to T2

this result will be delta_hbar which you then must divide by the molar mass of Nitrogen



[Edited on September 28, 2005 at 12:19 AM. Reason : add]

9/28/2005 12:17:35 AM

67 i thought P was constant

[Edited on September 28, 2005 at 12:19 AM. Reason : sad face]

9/28/2005 12:18:15 AM

ah ok I was down the completely right path. thanks

9/28/2005 12:21:19 AM

no, it just says PV^1.3 is constant until the volume is halved. therefore since the quantity is constant you can set up p2v2^1.3=p1v1^1.3. Solve for p2 and you get 2^1.3*100kPa =246.2kPa

sorry I left the decimal point out of the last one.

[Edited on September 28, 2005 at 12:35 AM. Reason : fdgdgf]

9/28/2005 12:34:06 AM

ok but I still don't get the right answer

I still need help on 67 and the last one

9/28/2005 12:12:26 PM

can someone please explain #41?
I never get the mixing tank questions right

10/3/2005 3:52:48 PM

i'll be in mann from 10:00 - 11:30 tomorrow morning with someone else if anyone wants to work on these with us

10/3/2005 11:24:23 PM

yea two tanks suck. I'm working on it, maybe ill be able to get somewhere.

What problems do we have to do? His e-mail is confusing - And the 54.8 kj and 13.6 kj for 62? Why is 66 before 62? Does he mean 67?

[Edited on October 3, 2005 at 11:35 PM. Reason : sdfsf]

10/3/2005 11:33:11 PM

yes, 67.

and for those tanks problems, start with the conservation of energy.

10/4/2005 12:55:40 AM

havent we already done 41 and 67?

10/4/2005 1:00:59 AM