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mahannan
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if a man is lifting weight while standing at rest, is he doing work microscopically?
Is Lifting Weight While Standing at Rest Considered Work?
In summary, the question of whether a man is doing microscopic work while lifting a weight at rest depends on the definition of work being used. In the physics definition, no work is being done as the weight is not moving. However, in the physiological definition, the muscles are still performing work as they continuously tense and relax, requiring energy. This topic has been discussed extensively in a previous thread, where the search function proved to be too slow.
- #2
Doc Al
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If he's lifting it microscopically.mahannan said:
Do you mean holding a weight without moving it? Or lifting a weight while standing in one place?
- #3
Hootenanny
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I think we have been through this discussion before, the physics definition of work is fundementally different to the physiological defintion of work. I'll try and dig out a link to the other thread.
- #4
mahannan
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I mean, do his muscles perform any work as he is standing while lifting the weight at rest?Doc Al said:If he's lifting it microscopically.
Do you mean holding a weight without moving it? Or lifting a weight while standing in one place?
- #5
Doc Al
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I will assume you mean that the man is holding a weight without moving it. In that case while there is no mechanical work done on the weight, there is certainly work going on in your muscles (they continually tense and relax)--that's why you get tired just holding a weight, even though you are not moving it. That internal work requires energy.
- #6
Doc Al
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We beat this one to death here: https://www.physicsforums.com/showthread.php?t=119026
- #7
Hootenanny
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Doc Al said:
You beat me to it Doc
Was your search function running slow? Mine took ages to display...- #8
Doc Al
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Yes, way too slow to be useful. But the thread wasn't that old, so I found it in the list.Hootenanny said:
1. What is work done holding a weight?
Work done holding a weight refers to the amount of energy expended to hold or lift a weight against the force of gravity. It is a measure of the effort required to overcome the weight of an object.
2. How is work done holding a weight calculated?
The amount of work done holding a weight is calculated by multiplying the weight of the object in kilograms by the distance it is lifted in meters, and then multiplying that by the force of gravity (9.8 m/s^2). This can be expressed using the formula W = mgh, where W is work, m is mass, g is gravity, and h is height.
3. What are the units for work done holding a weight?
The units for work done holding a weight are joules (J) in the SI system. In the imperial system, the unit is foot-pounds (ft-lb).
4. Does the weight of the object affect the work done holding it?
Yes, the weight of the object does affect the work done holding it. The greater the weight of the object, the more work is required to hold or lift it against the force of gravity. This is because work is directly proportional to the weight of an object.
5. Is work done holding a weight the same as work done by lifting a weight?
No, these are two different concepts. Work done holding a weight refers to the effort required to keep an object at a certain height against gravity. Work done by lifting a weight refers to the effort required to move an object from one height to another against gravity. The latter involves a change in the potential energy of the object, while the former does not.
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