what do you do next?

And so what you should do at this point is

do another drawing cut or section cut to continue to solve.

we'll do a joint cut at point P2.

And if I draw that free body diagram, I've got my 1,400 pound force

up and to the right. I have the 900 pound force down.

I have two components of my cut between P1 and

P2, I've got an x component and a y component.

I know that the x component, again, is the same throughout.

Because there's only, there's no external forces in the x direction.

So, I know right away.

That T12 in the x direction is a 1109.9 pounds, and so I can take that joint

cut now, and all I have to do is find the T12

in the y direction, its y component. So, to do that what should you

do? Okay and so what, what you

should have said is, okay I can just sum forces

in the Y direction so that it will be equal to 0.

I will choose up as positive and so I get the T12

y component minus 900 plus the y component

of the 1,400 force, which is 1,400 times

sine of 37.56 degrees equals 0. And if

you solve for T12 Y now, you find

it's equal to 46.67

pounds. So now I have T12 x component

and y component. I can use Pythagorean's theorem to sum

those up together. So T12 will be equal to

the square root of T12 X squared

plus T12 Y squared,

T12 X is 1109.9,

T12y we just found to be

46.67. So T12

overall is equal to 1111

pounds in tension.

Listen, now I've got this section, and this section, I'v got Y2,

I still need the tension in that segment and the sag at P1.

And so, think about what you do next and then come on back.

the cable segment from A to P1, I've drawn a free body diagram

of the cut at joint A, I know AX and I know AY.

I know the tension in the A1 section has to be 1,109 pounds again.

1,109.9 pounds because

of tension in the x directions, the x components are the same throughout.

I don't know the tension in the in the y direction and so you can do that.

do that on your own, come on back.

And then add it up, and find the overall

tension in the segment from point A to point P1.

Okay? What you should have done, sum, sum forces

in the y direction, you get TA1 in the y direction, is 546.7

using Pythagorean's theorem to add those x and y components together.

You get the overall tension in segment A1 to be

1,237 pounds of tension. So, all we have left

now is to find the sag at point P1, and so here's again a look at joint A.

I'd like you to now go ahead and solve for Y1

using geometry and similar triangles, I did it before in the last

module and so you should be able to do that on your

own this time, but if you do it then come on back,

we'll do it together, okay. So, let's look at these

similar triangles here. this 546.7

eh, relates to the y1 side,

and 1,109 relates to the

eight side, so I've got Y1 is

to 546.7 as eight is to

1,109.9. And so y1

ends up equaling 3.94

feet which equals the

sag at P1. And so we

finished all the parts of the problem.

And so that's the end of the

section on cable support systems supporting concentrated loads,

we'll come back next module and a look

at suspension type systems like this suspension bridge.

See you then.