# 'Slackline' equipment load formula (weighted line between 2 fixed points)

1. Jan 25, 2012

### eliotwebb

Hello,

I have a real world sports question I need help with:

I am looking for an accurate formula to calculate the load of Slackline equipment (will explain shortly), based on:

- The length of the line
- The sag of the line
- The weight on the line

Slacklining is like tight rope walking, but on a slack ribbon (usually 1 inch wide webbing)

There are various arguments on which is the best formula:

http://slack.e30tuner.com/articles_linetension.php

http://forum.slackline.com/archive/modules.php?name=Forums&file=viewtopic&t=1279&postdays=0&postorder=asc&start=0 [Broken]

http://www.slacklineexpress.com/force.php [Broken]

I thought it was worth a post to see what you all think.

Thanks for having a look,

Eliot

Last edited by a moderator: May 5, 2017
2. Jan 25, 2012

### Studiot

G'dday, Elliotwebb and welcome to Physics Forums.

Firstly let me admit to knowing nothing about the sport of slackline walking.

However from your description of the webbing and the picture in your third reference I would say that all are seriously deficient.

I say this because the line has appreciable width, whereas all the links assume a 'thin' stringlike model.

The point of this is that the width of the webbing is sufficient to transmit torque as well as tension (you can see that in the picture).
The addition of stresses due to both torque and tension being present is more complicated and clearly depends upon the relative values of each.

go well