Physics of the Slackline! Tension Forces in Slack Lines 

This is a physics tutorial in which we look at the large forces that can develop in slack lines; a classic problem in statics. We will use F = ma in both the horizontal and vertical directions to find the tension in a slack line. A slack line is a belt or strap that is tightened between two trees, often with a ratchet mechanism. It is pretty fun (and relaxing) to balance and walk on a slackline. First, we will look at a case in which the angle that the line makes with the horizontal is equal on both sides of the person balancing on it. Next, we will look at a scenario in which the two sides of the line make different angles with the horizontal. In both cases, it is important to realize that the horizontal components of all forces on the contact point will add to zero and the vertical components of all forces on the contact point will also add to zero. that is because the system is static; it is not accelerating. 0:25 Example 1 Equal Tensions on Both Sides 3:25 Example 2 Unequal Tensions on the Two Sides 4:20 Pause for Students to Practice 6:56 Slacklining in San Diego.