Can energy be in negative

Answer 1

It might, depending on how you define it. Especially in the case of gravitational potential energy, the "zero level" or "base level" is arbitrary; you might define the base level as ground level, for instance. In that case, any object above ground level has a positive potential energy, and any object below ground level has a negative potential energy. Ultimately, what matters is not how much potential energy an object "really has" - it is really hard to define or ascertain this - rather, what matters is how much the energy CHANGES from one position to another. The case is similar with voltages, which are related to potential energy in an electric field.