<commit_before>---
layout: post
title: "Physics of the Death Triangle"
tags: [Rock Climbing, Physics]
summary: Why the American Death Triangle is such a bad idea.
---
{% include JB/setup %}

<style>
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    width: 100%;
    border-top: 1px solid #ccc;
    border-bottom: 2px solid #ccc;
    color: #000;
    background: #fff;
    border-collapse: separate;
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<p>The <a href="https://en.wikipedia.org/wiki/American_death_triangle" target="_blank" alt="Wikipedia on American Death Triangle">American Death Triangle</a> is the classic example of a dangerously unsafe climbing anchor. It is incredibly easy to build, but also incredibly easy to avoid.</p>

<p>The reason the Death Triangle is such a bad idea is Freshman Physics, and is easily understood using <a href="https://en.wikipedia.org/wiki/Parallelogram_of_force" target="_blank" alt="Wikipedia on Force-Vector Diagrams">Force-Vector Diagrams</a>.</p>

<h3>The V Anchor</h3>

<p>First, let's look at a better anchor, the classic "V" anchor.</p>

<div style="width: 50%;margin: 0 auto;">
<table class="eqn-table"><tbody><tr>
 <td> <div style="float:left;">F = </div> </td>
 <td> <div style="float:left"> <div class="eqn-numerator">W</div> <div style="text-align:center;"> 2 * cos(&Theta;/2) </div> </div> </td>
</tr></tbody></table>
</div>


<h3>The Death Triangle</h3>

<p>Now let's look at the Death Triangle.</p>

<div style="width: 50%;margin: 0 auto;">
<table class="eqn-table"><tbody><tr>
 <td> <div style="float:left;">F = </div> </td>
 <td> <div style="float:left"> <div class="eqn-numerator">W</div> <div style="text-align:center;"> 2 * sin(&pi;/4 - &Theta;/4) </div> </div> </td>
</tr></tbody></table>
</div>

<h3>The Comparison</h3>

<p>The explanation above uses static forces and static loads. That is, the math/physics is simpler because nothing is moving. In reality, the most dangerous situation is when a climber falls, and for a short time they exert a much greater force on the anchor than just their resting weight.</p> 
<commit_msg>comparison thoughts.<commit_after>---
layout: post
title: "Physics of the Death Triangle"
tags: [Rock Climbing, Physics]
summary: Why the American Death Triangle is such a bad idea.
---
{% include JB/setup %}

<style>
table {
    width: 100%;
    border-top: 1px solid #ccc;
    border-bottom: 2px solid #ccc;
    color: #000;
    background: #fff;
    border-collapse: separate;
}
.eqn-numerator {
    border-bottom: 1px solid;
    text-align: center;
    margin-bottom: 2px;
    padding-bottom: 2px;
}
.eqn-table {
    border: 0;
    color: #777;
    font-size: 1em;
    font-family: Arial,Helvetica,sans-serif;
    width: auto; 
    margin-bottom: 2em;
}
</style>

<p>The <a href="https://en.wikipedia.org/wiki/American_death_triangle" target="_blank" alt="Wikipedia on American Death Triangle">American Death Triangle</a> is the classic example of a dangerously unsafe climbing anchor. It is incredibly easy to build, but also incredibly easy to avoid.</p>

<p>The reason the Death Triangle is such a bad idea is Freshman Physics, and is easily understood using <a href="https://en.wikipedia.org/wiki/Parallelogram_of_force" target="_blank" alt="Wikipedia on Force-Vector Diagrams">Force-Vector Diagrams</a>.</p>

<h3>The V Anchor</h3>

<p>First, let's look at a better anchor, the classic "V" anchor.</p>

<div style="width: 50%;margin: 0 auto;">
<table class="eqn-table"><tbody><tr>
 <td> <div style="float:left;">F = </div> </td>
 <td> <div style="float:left"> <div class="eqn-numerator">W</div> <div style="text-align:center;"> 2 * cos(&Theta;/2) </div> </div> </td>
</tr></tbody></table>
</div>


<h3>The Death Triangle</h3>

<p>Now let's look at the Death Triangle.</p>

<div style="width: 50%;margin: 0 auto;">
<table class="eqn-table"><tbody><tr>
 <td> <div style="float:left;">F = </div> </td>
 <td> <div style="float:left"> <div class="eqn-numerator">W</div> <div style="text-align:center;"> 2 * sin(&pi;/4 - &Theta;/4) </div> </div> </td>
</tr></tbody></table>
</div>

<h3>The Comparison</h3>

<p>What we see above is that the extra side on the Death Triangle anchor creates a much great force on the climbing bolts. This means a much greater force on the sling/webbing that the anchor is built from. These extra forces can pluck protection out of the wall and snap cords. And the discussion above works the same for anchors with more than two pieces of protection.</p>

<p>The explanation above uses static forces and static loads. That is, the math/physics is simpler because nothing is moving. In reality, the most dangerous situation is when a climber falls, and for a short time they exert a much greater force on the anchor than just their resting weight.</p> 

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