What are the equations for equilibrium in a pulley system?

[anglum]

The problem involves a picture so i posted it so it can be seen and easier or you guys to help me


i know that the total sum of the tensions in this need to equal 37.4N + 61.4N

but i get confused when angles get brought into play

link to problem

http://i199.photobucket.com/albums/aa314/anglum/help.jpg

 

[Doc Al]

Examine the first "knot". What must be true about the forces acting on that knot? Hint: Consider vertical and horizontal components separately.

 

[anglum]

i am so lost on this problem... would the forces actin on the first knot need to equal 37.4N?

 

[Doc Al]

Since the system is in equilibrium, the total force must be zero.

 

[anglum]

ok so if the total force on the first knot is 0 then i can assume that

37.4N + T1+T2 = 0??

 

[anglum]

i also need to find the other angles value in degrees as a part 4 of the question

 

[Doc Al]

ok so if the total force on the first knot is 0 then i can assume that

37.4N + T1+T2 = 0??

No, since forces are vectors and must be added as vectors. As I said earlier: Consider vertical and horizontal components separately.

 

[anglum]

i am totally lost right now... i don't see y the forces of t1 t2 and the weight don't equal to zero

 

[anglum]

the vertical componentei s37.4 and the horizontal is t2 ?

 

[Doc Al]

i am totally lost right now... i don't see y the forces of t1 t2 and the weight don't equal to zero

The vectors add to zero, but not just the numbers.

For each of those three forces list the following:
(1) x-component
(2) y-component

Some of the components will be zero.

 

[anglum]

ok for the wegith hangin down the x component is 0 and the y component is 37.4N

for T2 the horizontal is WHAT while the vertical is 0

and for T1 the vertical is sin41 = T1/X

and for T1 the horizontal is cos 41 = T1/X

 

[anglum]

ahhhh i figured out the first 3 parts

im stuck on the angle

 

[Doc Al]

ok for the wegith hangin down the x component is 0 and the y component is 37.4N

Since it's downward, call it -37.4 N.

for T2 the horizontal is WHAT while the vertical is 0

Call the horizontal component T2.

and for T1 the vertical is sin41 = T1/X

and for T1 the horizontal is cos 41 = T1/X

The vertical component is T1 sin41.
The horizontal component is -T1 cos41.

Now add up the vertical components and set to zero. Do the same for the horizontal components.