Is the (electrostatic) interaction energy always positive, or can it be negative?
123054
How can we have negative work in electrostatics, if $W=(\epsilon_0/2)\int\! E^2\ \mathrm{d}\tau$?
131958
Why is the potential energy equal to the negative integral of a force?
40485
Benefits and Drawbacks of Swapping Associations of Positivity and Negativity of the Proton and Electron
110489
Are there any known negative heat capacities?
51947
Is the Riemann integral of a strictly positive function positive?
12876
Why can't electrostatic field lines form closed loops?
111578
Why is gravitational potential energy negative, and what does that mean?
21186
Why is the second order perturbative correction to the ground state energy always down?
157534
Potential energy sign conventions
148463
How do I get the negative sign in the expression for Gravitational Potential Energy?
15105
How does positive charge spread out in conductors?
29256
Question on the hydrostatic paradox
92918
Positive work by a magnetic field
41209
Does matter with negative mass exist?
60289
How does QFT interpret the Negative probability problem of the real scalar fields' Klein-Gordon equation?
140005
How will a particle with energy less than $V_{\rm min}$ behave?
146039
Is it always possible to define energy of a system?