For number 3, use the formula Wdot = (deltaP)(Vdot)/efficiency, just make sure you convert your part a deltaP back to lbf/ft^2 and your Vdot = ft^3/s. Once you get this answer, convert to hp by dividing by 550.

11/9/2005 6:03:46 PM

for 5 this is what i got for my chart:

3 - 3.068, 4.3399, 102644, .000587, .000624, 58.67, -12061
2.5 - 2.469, 6.7011, 127544, .000729, .000502, 72.9, -25.691
2 - 2.067, 9.5611, 152349, .000871, .00042, 87.08, -41.007

can the head loss at 2 be negative? can head loss be negative in general?

11/9/2005 7:16:34 PM

my h2's were wrong, had a wrong sign:

3 - -13.306
2.5 - -14.2514
2 - -15.939

11/9/2005 7:58:09 PM

what length did you use for L/D i used 27ft i think you used 15 ft why?

also your f values are really small and arent even on the moody chart where did you get those?

and for your reynolds numbers did you use 6.73e-5 for mu instead of mu at 40*F which is 1.038e-3?

11/9/2005 8:03:53 PM

i used 15ft just cause it was the horizontal length but i guess its supposed to be the total length traveled? if that's the case it would be 27 then.

my f values i solved for using my reynolds number. f = 64/Re, came from the book.

for reynolds i found it by using kinematic viscosity instead of dynamic viscosity. i used the standard # in the chart on the front cover of the book.

11/9/2005 8:09:25 PM

Quote :

"For number 3, use the formula Wdot = (deltaP)(Vdot)/efficiency, just make sure you convert your part a deltaP back to lbf/ft^2 and your Vdot = ft^3/s. Once you get this answer, convert to hp by dividing by 550."

how did you get your delta p

i found the vdot to be 129.792ft^3/s; V to be 10.328 ft/s; and the Re to be 6.85e6; e/D=0.000038 -> f=0.01

is this what you got, if not, can you tell me where i went wrong

thanks

11/9/2005 8:29:46 PM

for 3, my Vdot=129.966 ft^3/s, V=10.34 ft, f=.0096, e/D=.000038, Re=8.606e7. my deltap=7263.03 psi. i'm confused on this 1 as well, not sure where i'm goin wrong.

[Edited on November 9, 2005 at 8:36 PM. Reason : 3 and 5 are the only 1's i cant get]

11/9/2005 8:35:43 PM

hey for number 1 I don't understand how to use the equation... where do I start out to get that shit... I got number 2 and 3 just fine... but one for some reason is confusing me

11/9/2005 8:55:14 PM

brain what was your overall equation for number 2, i'm like 10 psi off for some reason, can you post what you have for your final hshaft equation?

11/9/2005 9:34:34 PM

^^I used a friction factor f=0.016 with an Red of 1118225, and an e/D = 0.0000375 to get that from the moody chart. i got the same vdot and v as you, so if you just do f(L/d)*(v^2/2g)*rho*g with some stupid conversions (just dividing by 32.2 so basically dont multiply by g in the eq i just gave you), then divide by 144 to get to psi, you should get around 11,200 psi.
^You got to get your P1 value using P=rho*g*h with that water height he gave, then do (P1-0)/rho*g=(Sum of minor losses)*v^2/2g
I finished all of the probs bc im leavin for boston tomorrow, but i still made a copy of my hw so if yall got any questions get at me, ill check this some more tonite

11/9/2005 9:39:20 PM

well for 2 i didnt get his answer of 750, i got 746 which is prob just rounding and shit.

my overall equation for 2 is:
P1/(roe*g) + z1 - z2 = hpump + hLtotal. hLtotal is gonna be the quantity [f(L/d) + sum of k's]*(V^2/2g)

can we get some hints on 3 and 5 please from those that got them?

[Edited on November 9, 2005 at 9:43 PM. Reason : .]

11/9/2005 9:42:39 PM

what was your sum of K and velocity values, i want to know if i got those right


[Edited on November 9, 2005 at 9:47 PM. Reason : .]

[Edited on November 9, 2005 at 9:50 PM. Reason : ..]

11/9/2005 9:47:32 PM

sum of k = 12.2, v = 47.45 ft/s

11/9/2005 9:53:34 PM

god i'm retarded, i'm still not getting the right answer

damnit

11/9/2005 10:04:08 PM

i still cant get 3 or 5

11/9/2005 10:11:36 PM

ok, i'm being a pest but, what did you use to get your f value and L/D for number 2

for 3:
Vdot is 139.792 after converting from barrels>gal>ft^3
V=Vdot/A = 10.328
Re using rhoVD/mu = 1118225
e/d=0.000038 wich on the chart gets your 0.016
deltap/rho*g=f(L/D)(V^2/2g)(1/144) = 11249psi

then use the conversion wtjessup mentioned at the top of the page

11/9/2005 10:26:42 PM

what equation is hpump for #2?

11/9/2005 10:44:03 PM

how in god's name did u get that Re? i cant get anywhere close to that. what density r u using for Re and then for the deltap/roe*g equation?

f i found using e/D and the moody chart. there is no listing for galvanized steel so i think he meant galvanized iron since there is an entry; i used .0005 for e. L/D i found using 50/.0518.

11/9/2005 10:48:40 PM

I have all the same values as listed above for number three and still cant get it. I used rho to be 57.94, is that right?

is there a trick i am missing?

11/9/2005 11:27:30 PM

Nevermind the above post, i got it. Question now is, for h on the chart of number 5 what equation did you use to find that?

11/10/2005 12:21:26 AM

bttt for 9.5

11/10/2005 8:57:49 PM

i think my biggest problem is i can't figure out how to get some of this crap to convert

11/10/2005 10:13:38 PM

on number 2, it says a free discharge, so does that mean KL,exit = 0?

11/10/2005 10:36:54 PM

yes

11/10/2005 11:39:01 PM

so anyone going to be able to get pictures up of the homeworks? If somebody could that would be awesome....

11/14/2005 6:38:12 PM

Hey pictures of homework??? damn it... I guess I will go over and copy them for myself

11/15/2005 3:49:59 PM

oh darn no one did all the work for you, iwas going to take pics but my camera is broken, you'll remember more if you copy them down anyways

11/15/2005 4:19:04 PM

Quote :

"oh darn no one did all the work for you"

haha that's what I was thinking, at least ask nicely for them and don't complain

11/15/2005 6:58:14 PM

well he did ask nicely. just didn't get the response that he wanted. and besides . . . he is meanJay

[Edited on November 15, 2005 at 7:13 PM. Reason : ]

11/15/2005 7:13:17 PM

Is the test on the last three homeworks on last two?

He only has solutions to the last two, but 3 homeworks ago was also on Chapter 7, so I was just curious

11/15/2005 8:43:40 PM

all three homeworks, but he sounded almost like there wouldn't be anything on the dimensional analysis, but he could throw that in a problem with some kind of head loss type of problem in it

the dimensional analysis stuff wasnt that bad either way

good luck guys, i need a decent grade to keep a good average in there

i just hope it isnt quite as long as the last one considering i didnt have time to go back over that one and i lost about 10 points on stupid shit

11/15/2005 8:47:01 PM

i never got the solutions to chp 7 stuff either, but i'm pretty sure i did all of that stuff correctly anyways, nothing tricky about it

11/15/2005 8:47:52 PM

my bad.... i didn't mean to sound mad.... and yes I did want someone to do the work for me... but don't we all :-D.... aww just fuckin.... I got the solutions anyways.... I am sure I will do fine on the test.... just the head loss and pump stuff, is still killin me... I never did quite understand that stuff that much.... I guess we shall see tomorrow mornin

11/15/2005 10:35:06 PM

Well that first problem was fun

That second one, not so much

11/16/2005 9:14:45 AM

i didnt think it was too bad, second problem's wording tripped me up for a second, but i think i got it

11/16/2005 9:19:58 AM

well then you did a lot better on it than i did, haha

11/16/2005 9:25:45 AM

I think I did ok....I know a few stupid mistakes I made already though. I guess we'll just have to see.

11/16/2005 10:04:02 AM

yeah, it was pretty straight forward. should have been super easy.

I know I fucked up at least one part on the first one. Said omega was L /t instead of 1/t
Hopefully he only takes off for that once and not for carrying it through the problem.

The second one was just like HW / examples. I dont know what the hell my problem was. Hopefully either my grade isn't too bad, or everyone's grade is equally bad. But we shall see on friday.

11/16/2005 10:59:51 AM

^ see i agree, it should have been super easy

but for some reason i was just freakin out, and he came over and stood by me for like 10 minutes...I don't know why but that just totally threw me off, and then at the end I was rushing to get something down...no clue if my answers were anywhere close.

I'm 99% sure I did the pi groups right, so that's at least a 30

11/16/2005 2:33:24 PM

anyone know if the final is cummulative or just the last stuff we've been doing in there?

11/18/2005 10:56:31 AM

anyone get #5 for the hw? i'm havin trouble findin the drag force from the given info.

11/29/2005 12:08:26 PM

for some reason i just had a total memory lapse, did he move the homework to friday or is it still due tomorrow?

11/29/2005 8:47:33 PM

he said we could turn it in either day

11/29/2005 10:08:12 PM

cutie -- its cumulative unfortunately

11/30/2005 3:26:53 PM

yea I found that out... i asked that before he told us in class

anyone have any pointers for number 5?

11/30/2005 9:17:06 PM

You know that F=ma and terminal velocity is when it is no longer accelerating so F=0. Your two forces or the weight force in the direction down the incline and the drag force in the opposite direction of the velocity (up the incline). So the Fd = mgsin(12). Solve the Cd equation for V and then just evaluate it with the two different A's, and Cd's.


How do you do the irrotational part of 4?

12/1/2005 4:31:24 PM

so do any of you still have pictures of the solutions over the semester? Like an idiot I must have thrown them away when I would study them for an exam, so all I have are the uncorrected homeworks he passed back, and they aren't all completely right

12/2/2005 4:16:26 PM

haha it is so hard to study for this on a friday night

12/2/2005 9:32:33 PM

I've got no motivation at all for this crap tonight. So instead I'm watchin Waterboy and realxing. I figure if I don't it'll be harder for me to study the rest of the weekend.

12/2/2005 11:08:11 PM

this is gonna be fuuuuuuuun

12/4/2005 3:20:02 PM