What exactly is energy?
8178
What Is Energy? Where did it come from?
146039
Is it always possible to define energy of a system?
42186
When is the Hamiltonian of a system not equal to its total energy?
52598
How can I interpret "energy" in signals?
53052
What exactly is work?
97505
Singularity - exactly what is it?
57481
How exactly does  work?
107902
Is Kinetic Energy stored as (rest) mass?
131167
Kinetic energy of the object, but Potential energy of the system: Why is it so?
47395
What exactly is light?
11121
What exactly is voltage?
69885
What is an Electron?
133421
what type of energy electrical current have
122561
Is the energy always discrete?
98846
Why is Kinetic Energy = (-) Total Energy and Potential Energy = 2 $\times$ Total Energy?
17619
How does rest mass become energy?
155558
If energy is only defined up to a constant, can we really claim that ground state energy has an absolute value?