Forces and laws of motion worksheet-newtons first law

1. Nov 9, 2008

meredith

1. The problem statement, all variables and given/known data

http://go.hrw.com/resources/go_sc/phy/HF2SR042.PDF

this is the link to the worksheet im having trouble with. if anyone could help me out that would be great. i got most of it but have a few questions.

2. Relevant equations
fy=sin(angle) x force
fx= cos(angle) x force
fnet = √(fy^2 + fx^2)

3. The attempt at a solution
1.) F1 + F2 + F3
2.) String 1: x component:0
y component: -Fg
String 2 x component: -F2cos(theta1)
y component: F2sin (theta1)
String 3: x component: F3cos(theta2)
y component: F3sin(theta2)

Number 3 is what im having trouble with. i know that the Fx net is:
√0+xcomponent String2^2+x component String3^2)
but im not sure about the y component. is it just the sqrrt of the sums of the squares of the three ycomponenents? or am i missing something?
oh and i think i can do #4 without a problem.

so can someone check my work and make sure its right and help me with #3? thanks!

2. Nov 9, 2008

asleight

1) It's in equilibrium...

2) 0, $$F_1=m\textbf{g}$$.

3) It's in equlibrium in both directions...

4) Sweet.