Would one be pushing as much as their weight?

AI Thread Summary
The discussion centers on the mechanics of pushing weight in relation to a chest press machine and a chair lift. It highlights that while the work done may be equivalent, the effective weight being pressed can differ based on the distance ratio between the two movements. A mechanical advantage allows for a lower force over a longer distance, maintaining the equality of input and output work. The conversation emphasizes understanding how these principles apply to exercise equipment. Overall, the relationship between distance and weight is crucial in determining the effectiveness of the workout.
biomajor
Messages
2
Reaction score
0
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?

1700758031609.png
 
Last edited by a moderator:
Physics news on Phys.org
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.
 
berkeman said:
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?
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »
Thread 'Minimum mass of a block'

Thread 'Minimum mass of a block'

Here we know that if block B is going to move up or just be at the verge of moving up ##Mg \sin \theta ## will act downwards and maximum static friction will act downwards ## \mu Mg \cos \theta ## Now what im confused by is how will we know " how quickly" block B reaches its maximum static friction value without any numbers, the suggested solution says that when block A is at its maximum extension, then block B will start to move up but with a certain set of values couldn't block A reach...
View full post »

Similar threads

Work done by a normal force (or rather, work NOT done)
2
Replies
57
Views
5K
Forces involved in principle of virtual work
Replies
2
Views
732
Work done by a balloon that is rising
Replies
8
Views
760
Pressure question: Weight of a car calculated from tyre contact patch area
Replies
3
Views
891
About work done through exercise (push ups)
Replies
4
Views
3K
Why is the work done double its expected value? (conveyer belt)
2
Replies
58
Views
5K
In which circumstances is work done?
Replies
3
Views
1K
Is enthalpy just the sum of internal energy and work against external pressure?
Replies
5
Views
975
How much force does a moving car exert on to the road?
Replies
13
Views
3K
Does a person burn calories when lowering a weight?
Replies
9
Views
2K

Hot Threads

Recent Insights

Back
Top