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# Is it possible for a system to have negative potential energy?

A) No, because this would have no physical meaning

B) No, because the kinetic energy of a system must equal it’s potential energy.

C) Yes, as long as the total energy is positve.

D) Yes, since the choice of the zero of potential energy is arbitrary.

potential energy ( U )

U = m*g*y

m is mass

g is gravitational acceleration

y is height

The origin of your y axis IS arbitrary.

what the potential energy is at some point can be any value you want, positive or negative. what matters is the change in potential energy when you move from one height to another, and you will find that regardless of what you choose for a coordinate system or for your origin, you will always get the same value for a change of potential energy ( delta U ).

So the answer is ‘D’.

Let’s dig on this a moment…

Energy is manifested in work (newtons, I believe).

Potential energy is stored kinetic energy. Therefore…

Yes and no.

Yes, it is possible, in the sense that negative potential energy would be identical to the work that the positive (normal) potential energy is used to perform.

No, it is not possible if you define it in the strictest definition of the term… potential energy is positive. The closest you could come to negative potential energy in this sense would probably be a vacuum, which isn’t really NEGATIVE so much as inverted positive potential energy.

Hope this… err… clarifies things…

-Daniel

hmm I think it is D because whether or not the potential energy is positive or negative depends on your perspective. for example potential energy of a spring is P= -K*X, but X can be positive or negative.

A: Consider an object that needs to have potential energy added just to bring it equal to zero – bet you can’t.

D