Vector Force Problem: Understanding Horizontal Forces and Solving for Net Force

[1MileCrash]

The problem is attached.

I am supremely stumped. First and foremost, what the heck does "horizontal forces" mean? If they are both horizontal, how is the angle between them anything but 0/180??

Regardless..

The graph has a slope of 3, therefore acceleration's x component is 3. Therefore net force x-component is 5.1

Therefore,

2.6cos(a) + 9.0cos(b) = 5.1

But so what? That's all the information that the problem gives me. Granted I know that cos(a) has to be between 1 and 0 for it to be in the positive direction...

Any hints? I really have no idea!

 

[1MileCrash]

Problem is attached.

EDIT:

Am I reading this correctly? By F1 is in the direction of the +x axis, do they mean that as in it has no component along y? Or just that it's x component is positive?

Arrg, this is a terribly worded question. I really want to know what two "horizontal forces" are!

Solved, yes, they did just mean that F1 had a y component of 0. What a headache.

 

[SammyS]

Problem is attached.

EDIT:

Am I reading this correctly? By F1 is in the direction of the +x axis, do they mean that as in it has no component along y? Or just that it's x component is positive?

Arrg, this is a terribly worded question. I really want to know what two "horizontal forces" are!

Solved, yes, they did just mean that F1 had a y component of 0. What a headache.

It seems clearly worded to me. Yes, it does take some thought to get some of the details straight, but I don't consider it ambiguous at all.

As for your earlier question about horizontal forces, it's clearly worded that the xy-plane is horizontal. That gives two dimensions.