What is the minimum force required to keep two cables taut at a given point?

[fociboy]

The cables are tied at A and loaed as shown
Determine the range of values of P for which both cables remain taut !
http://www.freeimagehosting.net/uploads/27fcfeba9a.jpg

I have an idea on the AC rope. Since the tension force T must not be zero on the horizontal line (or the line along AC), therefore, the min force of P > 0. Because when P>0, the horizontal component is not zero. Is it true? How about AB

 

[tiny-tim]

Welcome to PF!

Hi fociboy ! Welcome to PF!

If P is too small, the 960N weight will pull A toward the wall.

If P is too large, it will pull A upward.

Hint: the question is really asking you find the formulas for the tension in each cable.

Then you choose the values for which the tension in either cable is zero.

 

[fociboy]

Dear tiny-tim,
I've known how to solve it. We resolve all the force into x and y component. And determine the conditions that the tension force on the rope is more than zero

 

[tiny-tim]

Hi fociboy!

Dear tiny-tim,
I've known how to solve it. We resolve all the force into x and y component. And determine the conditions that the tension force on the rope is more than zero

(you mean I know how to solve it, or I've found how to solve it )

That's right … resolve into components.

Is everything ok now?

 

[fociboy]

I see. But you know, I've started studying in university and there're still a lot of things to know. I hope I can join and become an active member of the forum. Thanks :)