Question

Is it possible for a system to have negative potential energy? a) No, because this would have no physical meaning.b) Yes, as long as the kinetic energy is positive.c) Yes, since the choice of the zero of potential energy is arbitrary. d) Yes, as long as the total energy is positive.

Answer 1

Answer: c) Yes, since the choice of the zero of potential energy is arbitrary.

Explanation:

Potential energy depends on the frame in which you are looking at the system.

For example, the potential energy of a lifted object can be written as:

U = mgh

where m is the mass, g is the gravitational acceleration and h is the height of the object.

But the height depends on where we have the zero if the zero is in the ground, then and h = 5m, then the potential energy is positive, but the 0 is the ground of a cliff, and the object is falling down the cliff, then we will have a negative value for h, which implies that we have negative potential energy.

This means that if we want to make the potential energy equal to zero, we must apply kinetic energy to the object (for example, grabbing it and throwing it upwards). On the other hand, if the potential energy is positive, this means that the object will "produce" kinetic energy as the potential energy starts to decrease. For example, an object that is dropped from a three (with an initial kinetic energy of zero) and only potential energy, and as the object falls to the ground the potential energy goes to zero and transforms completely in kinetic energy.