If I’m hanging onto something, it’s being pulled down by my weight. But if I do a pull-up, does it get pulled down with more force or is it unchanged?

Question

I tried to do think it out but I can’t really wrap my head around the math and where to start.

In: 5

Answer 1

When you start pulling, you accelerate up. By Newton’s 3rd law, the bar needs to be pulled down more. From then, if you ascend at a constant velocity, the bar is only experiencing your weight. When you reach the top and slow to a stop, you are accelerating downward, so the bar experiences less downward force until you stop again. Hanging with your arms flexed means the bar only holds your weight.

It would look like this on a graph

—-^—-v—-

First flat section is just hanging, then they start ascending, then the next flat section is the ascent, then they stop, and the last flat section is hanging with the arms flexed.