Would one be pushing as much as their weight?

[biomajor]

Homework Statement

In the following video, there is a machine. https://youtu.be/a_CGlAnxO5c It looks like a chest press machine but doesn't have weights attached - only attached to the chair. Would one be lifting as much as they weigh?

Relevant Equations

I was thinking it might have something to do with W = F•d

Because one is effectively pushing in the same way as a chest press machine, wouldn't the work done be the same?

 

[berkeman]

Welcome to PF.

Yes, it does look like how you describe it. The only caveat would be the ratio between the chest press distance and the chair lift distance. I couldn't tell if it was 1:1 or maybe more like 2:1. The work will still be the same, but you would only be pressing half of your weight in the latter case.

 

[biomajor]

Welcome to PF.

Yes, it does look like how you describe it. The only caveat would be the ratio between the chest press distance and the chair lift distance. I couldn't tell if it was 1:1 or maybe more like 2:1. The work will still be the same, but you would only be pressing half of your weight in the latter case.

Hello! Thank you for the warm welcome!
If it is not too much trouble, may I ask how the ratio would change the weight but not the work? I imagined it as a pulley system so the weight would be the same but the work done would change because of differing distances? Is this an incorrect way to look at it?

 

[gmax137]

Hi @biomajor
Mechanical advantage allows less input force over a longer distance. The input work (lower force times longer distance) is equal to the output work (higher force, less distance). Try this explanation:
https://en.wikipedia.org/wiki/Simple_machine