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

Imagine yourself floating in space without the earth below you, or the bar above you, doing the same motion as a pull up. You’re essentially pulling your arms down, and your legs up.

Even though the earth is below us pulling down, it’s still not that much different than being in space. If you consider yourself the “center,” of the system, then you’re still pulling the bar down, however the earth just so happens to be pulling both you *and* the bar down at the same time you’re pulling the bar towards you.

ELI13: As a physical object you still have inertia, meaning the mass of your body just like any other physical object resists speeding up or slowing down. This inertia acts as a sort of “anchor,” which wants to hold you in place, so as you try to pull yourself towards the bar, you’re not just overcoming gravity, but your stationary inertia as well, and the bar has to counteract that extra force. If it doesn’t counteract that force, then the bar will move towards you i.e. break and hit you in the face.