Calculating Work Done by Tension in Vine for Tarzan

[Miike012]

Tarzan, who weighs 875 N, swings from a vine through
the jungle. How much work is done by the tension in the
vine as he drops through a vertical distance of 4.00 m?

The answer is zero.

Why is this?

 

[PhanthomJay]

You might want to draw a sketch of King of the Jungle as he swings from a long vine. At some point he is 4 m vertically lower than his starting point. The tension force in the vine is always perpendicular to his displacement vector at any instant. What is the definition of work?