Wonder if the test didn't go so well . . . there seem to be more example problems then normal in the new notes

9/15/2005 4:56:32 PM

theres also a lot more different variations of these kinds of problems

9/15/2005 6:54:56 PM

So how did everyone do on the test?

9/16/2005 1:04:07 PM

I'm happy with what I got

the homework also looks exactly like the example problems we will be doing in class

[Edited on September 16, 2005 at 1:16 PM. Reason : hw]

9/16/2005 1:15:34 PM

i did a hell of a lot better than i thought i would thats for damn sure

9/16/2005 4:27:56 PM

hey has anyone got the answer for #1 on the homework yet? How do you do it?

9/21/2005 9:05:29 PM

ditto on #1

9/22/2005 12:20:08 AM

yeah i have the answer, i'm confused on 2 and 3 if anybody can help with that...

1:
m1 = -|pv1a1|
m2 = -|pv2a2|
m1 + m2 = m3
m3 = |pv3a3|

solve for v3 = 9.33333m/s

find components of v3 -> v3x, v3y using angle

should give you 8.0829i - 4.66666j

if anyone has number 2 or 3 done, i missed class when he went over the examples like these and the book isnt much help

thanks

9/22/2005 12:28:11 PM

I'm about to start on it. Will let ya know

9/22/2005 1:30:09 PM

anyone able to integrate #2 correctly? i come close to the answer but never actually get what he has. i dont know waht i' doin wrong but i have a feelin its with my integration. i hate integrating trig functions. grr.

9/22/2005 3:36:46 PM

yeah, i got what he got for the second one. Kinda stuck atm on the third one and I have to run. Be back around 8

9/22/2005 5:10:30 PM

can someone explain what you integrate for the second one... i dont have anything to go by

thanks

9/22/2005 5:31:35 PM

i followed the example we did in class but i'm doin somethin wrong with the integral cause like i said, i get somethin close to the answer but not actually it.

9/22/2005 5:37:24 PM

can you write it out for me, i missed the class where he went over that example

i'd appreciate it, i've got 1 and 4, but 2 and 3 i dont have an example to follow

9/22/2005 5:43:21 PM

^ i PM'ed ya

9/22/2005 6:18:35 PM

can anyone explain to me how to do the integral for number two? I know it sounds dumb...but I keep getting 0!!!

9/22/2005 7:46:45 PM

quick question about number 3...I think my problem is trying to determine what V2 should be labeled as. I tried using that in class example and used V2 = (Vmax*(y/h)j), but solving for that brings me down to eventually having V1=Vmax/2, and that's not right.

What should I be using as my V2?

9/22/2005 8:28:47 PM

I got the same exact thing! I don't know...

9/22/2005 9:00:46 PM

Alright nope I'm confused on #3. I know he did a simillar example in class but that isn't at a 90 degree angle. Do you have to deal with the angle in #3?

9/22/2005 9:27:22 PM

all it should do in this case is change the directions for your dot product and maybe change a y to an x or somethign along those lines

and which example are you talking about? 5.6?

[Edited on September 22, 2005 at 9:51 PM. Reason : ]

9/22/2005 9:50:31 PM

Has ANYONE gotten #3???

9/22/2005 10:27:52 PM

laura, i wasnt gettin zero for the integral but i still wasnt doin it right either..lol

9/22/2005 10:46:00 PM

has anyone gotten anything for #4?

9/23/2005 12:29:26 AM

the example 5.2 IN THE BOOK is the exact same as problem 4, just change a few variables

9/23/2005 1:13:05 AM

so has anyone gotten anywhere on the new HW problems?

9/28/2005 3:46:38 PM

just started

for #1, do we assume frictionless from 1-2 but not frictionless from 2-3?

9/28/2005 4:42:26 PM

got 2 and 3, still not getting 1 totally right, i'm getting about .5 less than the correct answer

any help?

9/28/2005 6:09:59 PM

hah, might help to read my fucking emails...

9/28/2005 6:58:59 PM

haha, yeah... he did that whole email thing today

9/28/2005 8:46:09 PM

can someone tell me what they got their P2 to be for number one? I can't figure out what i am doing wrong and that is what i keep coming up with is maybe P2. What conversion factor do you use? lbf to lbm by 32.2?

9/28/2005 9:25:21 PM

For the first problem, you can just use P=rho*g*h and leave the units in lbm because they will cancel out in Bernoulli's equation when you divide the pressure by density again. You'll only use 32.2 ft/s in the pressure equation that you'll need at point 2.

9/29/2005 8:05:16 AM

so anyone figure 1 out fully?

9/29/2005 1:10:58 PM

just finished it . . . i dont know y everyone said #1 was so hard

just state your assumptions and apply them to bernouli's equation and the rest is just math

P1--> Patm
V1-->0
z2-->0 (set your axis at the axis of the pipe)

solve bernouli's eqn for V2, then multiply that by the area of the pipe to get the flow rate.

[Edited on September 29, 2005 at 4:11 PM. Reason : ]

9/29/2005 3:57:00 PM

yea i got it as well. i wasnt setting my axis right so i kept gettin weird ass numbers.

9/29/2005 3:58:21 PM

anyone else still having problems with the HW?

9/29/2005 4:58:06 PM

I'm stuck on 5.2..
I set up bernoulli's equation and got v_1 in terms of v_2 so that I could solve for d/dt*Vol
How am I supposed to find v_2?
Is there a better way to solve this problem?

9/29/2005 5:39:49 PM

assume there is steady flow, there should be no d/dt term.

9/29/2005 5:40:44 PM

Yea I got that one by d/dt*vol I meant the volumetric flow rate which is v*A.

for number 3 if you use the equation associated with a pitot-static tube:
v^2=2*(P_0-P)/rho

What do you use for the P_0 and P??
I used atmospheric for P_0 and I used P as the pressure pushing on the manometer to solve for h.
-but my height is 5 inches to big...

9/29/2005 6:51:58 PM

you dont use a different thing for P0 and P1, you say that:

Po - P1 = deltaP

deltaP = gamma*h

9/29/2005 10:18:23 PM

for number 2 how do you get your v1?

9/29/2005 11:25:18 PM

anyone started the hw yet?

first one doesnt look bad, i'm gonna need some help on the 4th one though..

i'll post back when i try all of them tonight

10/2/2005 4:37:20 PM

anyone have any hints on 2, 5, or 6 ???

i think i have the other 3 right

10/4/2005 4:40:00 PM

Can anybody explain the difference between V and U, I am really getting confused when putting these into the equations? Thanks.

10/6/2005 7:47:48 AM

hmm, not 100% sure without looking im my notes

but i believe u is the velocity of the control volume in the y direction and u is the velocity of the CV in the x direction

10/7/2005 1:23:15 AM

Have most of yall finished this homework already?

I was going to do it right now, but found out I left some stuff I needed back at school

10/7/2005 11:56:28 AM

i still have 2 more to do, i think i have the other 4 right

i dont have 2 or 6 i think...

10/8/2005 11:56:39 AM

for #1 i am assuming we have to find FsubRx because of the coupling force. i have a final equation and my units work out to be Newtons but the actual number isnt working out to be what he has. did anyone actually get what he has?

10/8/2005 4:00:46 PM

how is the wire in tension in #4?

10/8/2005 4:17:27 PM

for example problem 6.5 we did in class, can someone explain to me why Vsubxyz1 = (V-U) and why Vsubxyz2 = (-V-U)sin60...?

10/8/2005 9:03:36 PM

so for #6 on the hw i got -29.7 m/s but the answer is 29.7. anyone else get a negative?

10/8/2005 10:13:34 PM