Bjarne
Philosopher
- Joined
- Oct 6, 2009
- Messages
- 5,075
If I were to eat at McD, I would actually loose weight since I hate the stuff they sell. ..Nevermind...
As somebody already explained, doing work to climb stairs is going to make you loose weight. The carbohydrates you burn to get the energy will turn into CO2 and water. You will exhale the CO2 and sweat and evaporate the water.
Your always wacky practical examples aside, what if we take a 1 kg weight and hoist or carry it to the top floor of a large building? Will it gain weight?
No it will not gain weight. (Weight is the the strength with which gravity pulls at an object in its actual position.) Since it is now a little farther from the Earth's center of gravity, it will actually weigh a little less. A good precision scale will be able to measure that.
Will it gain mass, then? (Mass is independent of the current gravity field.) No it will not gain mass. How about the potential energy, then? Well, potential energy resides in the system. When it is positional energy, as in this case, the system includes two objects, with a gravity field between them. The objects are the 1 kg weight, and Earth. Together, they will have gained a little bit of mass, but there will be no way you can see or measure any effect on the weight.
Read and understand, Bjarne, and you will actually be a little wiser.
Hans
This is a total mishmash of weight and mass. Weight is not a subject, so keep that out.
Even though there is almost always is a certain energy "lose" to bring a body to higher position, - at least some of the energy used in such a process, is simply converted to what you call potential energy, and this and only this is the point.
The expression; - “Position energy" is only an almost empty expression, at least seen from a mathematical point of view, - which in fact violate the equation E = Mc^2, so long your are not willing to admit that the added energy must be somewhere, in the real world..
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