Final answer:
The potential energy of a system can be positive, zero, or negative depending on the situation, unlike kinetic energy which is always positive or zero.
Step-by-step explanation:
The potential energy of a system can be positive, zero, or negative, depending on the situation.
Unlike kinetic energy which is always positive or zero, potential energy can take negative values in certain scenarios.
For example, if a spring is compressed, it stores potential energy which is negative.
On the other hand, if an object is lifted to a certain height, it gains gravitational potential energy which is positive.
Therefore, the statement that the potential energy of a system must always be positive or zero is not true.