There is a thing called energy?

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In summary, the conversation discusses the equation v_f^2-v_0^2=2ax and its application to different motions involving forces. The equation can be rewritten as KE difference = work done and is used to define energy. It is noted that energy is mainly defined mathematically and there is still no clear understanding of what energy truly is. Feynman's quote is mentioned to emphasize this point.
  • #1
kishtik
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[tex]
v_f^2-v_0^2=2ax
[/tex]
Multiplying by m,
[tex]
\frac{mv_f^2-mv_i^2}{2}=max
[/tex]
[tex]
\frac{1}{2}mv_f^2-\frac{1}{2}mv_i^2=Fx
[/tex]
This equation is true for all of the motions which include a force. Therefore we call the left side KE difference, and the right side work done.
Is energy a thing which can only be defined mathematically? Or are there any other ways to define it? If yes, why did Euler call it vis viva? Was it only because of KE? If no, what leads us to conclude that there is a thing called energy?
For almost every physical definition, we have an imagination, a perception, a conception, something inexplicable. Where is this coming from? When we were babies, playing with Legos (K'Nex for me) we learn about dynamics and perhaps energy. I've read that smells, tastes and views were perceived the same by a little baby. Perhaps we develop that conciousness at that age.
 
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  • #2
This only works if a, m, and F are constant, in general. Otherwise, you have to integrate.
 
  • #3


Originally posted by kishtik

Is energy a thing which can only be defined mathematically?
For the most part that is true. Recall what Feynman said on this point
It is important to realize that in physics today, we have no knowledge of what energy is. We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. However, there are formulas for calculating some numerical quantity, and we add it all together it gives “28” - always the same number. It is an abstract thing in that it does not tell us the mechanism or the reasons for the various formulas.
 

What is energy?

Energy is the capacity of a system to do work or produce heat. It is a fundamental quantity in physics and is present in all forms of matter and energy.

How is energy measured?

Energy is measured in joules (J) or in other units such as calories or kilowatt-hours (kWh). The amount of energy present in a system can be determined by measuring the work done or the heat produced.

What are the different forms of energy?

There are many different forms of energy, including kinetic energy (energy of motion), potential energy (energy stored in an object), thermal energy (energy due to temperature difference), and electromagnetic energy (energy carried by light and other electromagnetic waves).

Where does energy come from?

Energy cannot be created or destroyed, it can only be converted from one form to another. The ultimate source of energy on Earth is the Sun, which provides light and heat that is converted into various forms of energy by living organisms and natural processes.

Why is energy important?

Energy is essential for all living organisms and plays a crucial role in the functioning of the universe. It is used to power everyday activities, such as transportation, heating and cooling, and electricity. Without energy, life as we know it would not be possible.

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