# Help with applications of vector addition

1. Jul 7, 2010

### diana7

I can't seem to draw this diagram.
A sign weighing 98N is suspended from the middle of a 4m long chain. The ends of the chain are attached to a ceiling at points 3m apart. Okay so i drew a diagram with a horizontal that is 3m and the chain hanging from each side is 2m long and the object is 98N. I'm not sure if its right because I'm not getting the answer that the textbook gives. And the question is to determine the tensions in the chains.

2. Jul 7, 2010

### pgardn

What angle did you get between each part of the chain and the ceiling to which the two ends of the chain are attached?

3. Jul 7, 2010

### diana7

I got 97 degrees, but it's not right. My friend told me that it is 41.41 degrees.
i did cosx = (2^2+2^2-3^2)/(2*2*2)
that I used the cos-1 to find the degree

4. Jul 7, 2010

### diana7

I think i got it. i found my mistake! Thanks

5. Jul 7, 2010

### pgardn

So you know how to do the whole thing now?

6. Jul 7, 2010

### diana7

yupp. i had to divide 97.18 by 2 = 48.59
then I find hte angle since its a right angle triangle now. 90-48.59 = 41.41
then i know that the tension has to balance
so tsin41.41 + tsin41.41 = 98
2tsin41.41 = 98
t = 98 / (2sin41.41)
and i got the answer :) thanks for making me catch my mistake lol