Good at Physics??... need help.

[mAdMaLuDaWg]

Ok,
I've got one day to do a whole bunch of problems in Physics and I'm really stuck at this one. Could someone point me in the right direction and help me solve it?
Thanks a million in advance.

[LinuxNewbie]

i got 17.3 inches
i'm currently sketching it up with MS paint gimme a min here

I'M DONE
let me explain why that side with a Y next to it is 20. this is an equalateral triangle where all 3 angles are the same, for all angles to be the same, all lengths must be the same as well
the top is 10 because it's half of the length

man i'm just that l337

[LinuxNewbie]

have to make new post to attatch my beautiful drawing from MS Paint

[mAdMaLuDaWg]

Whoa buddy,
I wish it were that easy but unfortunately its not... I've seen u've considered the system to be in a 2-D plane but its in 3-D. Also you didn't take into account the conditions for the system to be in equilibrium.

I've got the concept on how to solve it but I don't know where to start.
Here is what you have to work with :
For the system to be in equilibrium the sum of the components have to be 0. I think the sin components of all the three 10 lb balls come into play here so its 3*TensionIn10poundstrings*sin(angle)j
The 15 lb ball is resolved into -15j (as it acts straight down)

Tks for the effort LinuxNewbie.

[LinuxNewbie]

ok i see the error now... the string is not straight down as indicated by my drawing.... let me think for a bit here.

[mAdMaLuDaWg]

Sorry bout the writing... the triangle where everything is 20 inches is taken to be 60 degrees because its equilateral, so all the angles are 60 degrees... and yes this is a college problem

[LinuxNewbie]

hey is there a way to find out how much it is being pulled into the center, like what angle it is from the Y axis to the center from the pully? if i have that angle into the center as well as the work i've already done, i could probably figure it out... i'm not quite at that stage of complicated physics just yet.

it's hard to think of an answer but here is my theory.
if we had the angle from the Y axis to the center, we would draw a right triangle and my 17.3 would be the hypotinuse then we would easily sine or pythag the answer out... or something.

[mAdMaLuDaWg]

Yep, u u gots to have that angle... I need that angle too ... no clue on how to find it...

[LinuxNewbie]

hey wait a minute.

the angle from the X axis (based at the top of this thing) to the string connecting to the center is 60 degrees right? wouldn't that make the angle along from the string connecting to the small weight to the big string in the middle 30 degrees? let me work this out here...

[mAdMaLuDaWg]

Umm nopes... the angle relates to the 20 inch triangle... not the string...
I really doubt u could solve this using pure trig....

I really appreciate the effort LinuxNewbie .