Total work/effort/energy spent to climb a hill

  • Context: Undergrad 
  • Thread starter Thread starter Stella.Physics
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    Hill Work done
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Discussion Overview

The discussion revolves around calculating the total work, effort, and energy expenditure involved in climbing a hill, specifically focusing on the physics of work done against gravity and the additional factors affecting energy consumption during movement. Participants explore various aspects of the problem, including potential energy, horizontal motion, and the inefficiencies of the human body.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant calculates the work done against gravity using the formula W=mgh, estimating work for a 60 kg person climbing a height of 200 m.
  • Another participant argues that this calculation is insufficient as it does not account for horizontal movement or the inefficiencies of the human body during physical activity.
  • Some participants propose that the total work should include both vertical and horizontal components, questioning how to incorporate the effort required for horizontal motion.
  • There is a discussion about the role of metabolic activity and energy loss, with some suggesting that factors like sweating and other bodily functions should be considered negligible.
  • One participant mentions that the work done against gravity does not include the energy expended during horizontal movement, which can significantly increase the total energy expenditure.
  • Another participant introduces the concept of work done by a minimum force required to push an object up an inclined plane, discussing the implications of friction and incline angle.
  • Concerns are raised about the relevance of calories burned in relation to the physics of the problem, with some suggesting that the discussion may be better suited for a health forum.
  • There is a debate about whether the energy consumed while walking downhill should be considered, with differing views on its relevance to the overall calculation of work.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the total work required to climb the hill, with multiple competing views on how to account for horizontal motion, metabolic factors, and the distinction between work and effort. The discussion remains unresolved regarding the best approach to calculate total energy expenditure.

Contextual Notes

Limitations include assumptions about efficiency, the neglect of metabolic activity, and the complexity of human movement compared to simple mechanical models. The discussion highlights the challenges in accurately modeling energy expenditure in physical activities.

  • #31
Merlin3189 said:
I'm not sure how his muscles pull him up, or how forces come from your body. I can see how you apply forces to other objects, but not how you apply a net force to yourself.
Have you come across Newton's third law?

Anyhow, if I understand your answers, I should be able to run up an icy hill much easier than up a rough hill:
View attachment 97267

the third law says about action and reaction but of course these two are applied to different bodies. like i create and push the ground and the ground pushes back.
also in a theoretical model yes, because in reality you would slide down and the go back and try again so the effort would be much more. on ice there is less friction but then you have the slippery aspect :P and as we know we walk and move around thanks to friction, that's why you can't move up an ice hill because the friction is minimum
 
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  • #32
Stella.Physics said:
the third law says about action and reaction but of course these two are applied to different bodies. like i create and push the ground and the ground pushes back.
And I think, the ground pushing back is the forces of friction and normal reaction. You pushing down on the ground is opposed by the ground pushing up on you, and you pushing backwards on the ground is opposed by friction pushing forwards on you. Which is where I start to get concerned about the work we do against friction when walking.

Anyhow, this is getting a bit away from ur original Q. My point was simply that the work done going horizontally was not work against ground friction, but work lifting legs and feet over the ground.
 

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