# Why do we consider the tension in a taut cable to be zero Newtons or Pound Force?

I have been browsing for a few hours now and I can't seem to find a reason for why this assumption is made for calculations and such in engineering problems like statics. It's a little embarrassing to be where I am now and not fully understand this, but I know it comes down to a lack of understanding in physics/mechanics. So here I am with the question:

Why do we consider the tension in a taut cable to be zero Newtons or Pound Force? For example, if I pull on a cable, with a force P, that is attached to a fixed joint/point on a wall and I say the cable is taut, the tension in the cable can be assumed to be zero. Typically I see this sort of assumption in "finding the range of values" type of problems.

I assumed that if the cable is taut it must be under tension due to the applied force, so therefore the tension must be greater than zero, but I was wrong. Wouldn't a tension of zero be due to slack in the cable?

I understand that this isn't a do-my-homework forum and this isn't meant to be that kind of question, but if it appears to be, please let me know and I'll work my magic to change it up. Also, if this has been answered before, I'd greatly appreciate the link. Thank you in advance to those who are willing to help me out with my lack of physics knowledge and I'm excited to hear what you all have to say!

• A cable cannot be taut if it has zero tension (unless you are in space). Commented Apr 25, 2017 at 3:23
• Net force on a cable is zero if the cable is not accelerating. This does not imply anything about the tension in the cable. Commented Apr 25, 2017 at 4:48
• @Yashas Whether it's in space doesn't seem to be relevant. A cable can be positioned to be perfectly straight on Earth or in space. But a taut cable is always under tension, by definition (etymonline.com/index.php?term=taut). Commented Apr 25, 2017 at 5:40