How Much Energy is Spent Holding 1kg for an Hour?

  • Context: High School 
  • Thread starter Thread starter jc.int
  • Start date Start date
  • Tags Tags
    Energy
Click For Summary

Discussion Overview

The discussion revolves around the theoretical energy expenditure involved in holding a 1-kilogram weight at a height of one meter for an hour. It explores concepts related to work, energy, and the biological efficiency of muscles, as well as comparisons to mechanical systems like helicopters and helium balloons.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asserts that no work is done when holding an object stationary since the displacement is zero.
  • Another participant notes that while no mechanical work is done, the body expends energy due to muscle inefficiency, which involves alternating contractions and relaxations.
  • It is mentioned that the energy expended by the body depends on factors such as muscle tone, circulation, and metabolism rather than just the weight and gravity.
  • A comparison is made to a solid table, which does not expend energy when holding the weight, highlighting the difference between biological and mechanical systems.
  • One participant questions the energy use of a helicopter holding a weight, suggesting it compensates for gravitational force.
  • Another participant responds by comparing a helicopter to a helium balloon, stating that the latter requires no energy input to hold a weight.

Areas of Agreement / Disagreement

Participants generally agree on the distinction between mechanical work and biological energy expenditure, but there are competing views regarding the energy dynamics of different systems (e.g., helicopters vs. balloons) and the implications of muscle efficiency.

Contextual Notes

The discussion does not resolve the complexities of energy expenditure in biological systems versus mechanical systems, nor does it clarify the assumptions underlying the comparisons made.

jc.int
Messages
16
Reaction score
0
hello,
If I hold 1kilogram at one meter of the groud during an hour, what would be the theoretical energy I am spending (in joules for example)?

Thank you,
Jaimie
 
Science news on Phys.org
You're not doing any work because the displacement of the object is 0.

However, your muscles, as a biological system, are inefficient. To just bear a load without moving it, they must alternately contract and relax rapidly. As a result, your body expends chemical energy and you do end up feeling tired.
 
cepheid said:
You're not doing any work because the displacement of the object is 0.

However, your muscles, as a biological system, are inefficient. To just bear a load without moving it, they must alternately contract and relax rapidly. As a result, your body expends chemical energy and you do end up feeling tired.

Indeed. And as a result, the amount of energy expended depends more on your muscle tone, circulation, metabolism, etc. then on simple physics of the weight and gravity. Place the same kilogram on a solid table for an hour and it becomes obvious that no energy is being expended (the table does not run down its batteries/use up its fuel, etc.)
 
I agree with you but when a helicopter holds a weight it is using energy to compense the gravity force, isn't it?
 
Yes, because once again, it is inefficient. A helium balloon can hold a weight as well, and it would require no energy input to do so.
 

Similar threads

Undergrad Nuclear power plant vs coal power plant efficiency
  • · Replies 32 ·
2
Replies
32
Views
6K
High School Energy Harvesting: Calculating kWh from Motorway Traffic
  • · Replies 4 ·
Replies
4
Views
2K
High School Energy seems to disappear when gas is compressed?
  • · Replies 3 ·
Replies
3
Views
2K
High School Compressed R134A refrigerant as a store of energy?
  • · Replies 5 ·
Replies
5
Views
2K
Graduate Is this a new and useful source of energy?
  • · Replies 5 ·
Replies
5
Views
1K
Undergrad How much energy is needed to blow up stone (and other materials)?
  • · Replies 28 ·
Replies
28
Views
4K
High School Energy transfer water > air in a greenhouse
  • · Replies 5 ·
Replies
5
Views
921
High School How Are Joules and Newton's Energy Transfer Related?
  • · Replies 15 ·
Replies
15
Views
3K
High School Basic thermal energy transfer physics: Insulation value in open airways vs sealed airways
  • · Replies 4 ·
Replies
4
Views
841
Undergrad Identification of changes in internal energy with work (in Callen's Thermodynamics)
  • · Replies 5 ·
Replies
5
Views
1K