Chapter 26, Problem 1PQ

What does it mean when a force is negative? What does it mean when the potential energy is negative?

To determine

The meaning of negative force and negative potential energy.

Answer to Problem 1PQ

The negative sign of force indicates that it is acting in a direction opposite to one which is defined as positive. Negative potential energy means the system has an energy less than that of the reference configuration with zero energy.

Explanation of Solution

Force is a vector quantity; it has both magnitude and direction. The negative sign of force means it is acting in a direction opposite to the direction which is defined as positive.

If the energy of the system is less than the energy of a reference configuration with zero energy. Then potential energy is said to be negative.

Conclusion:

The negative sign of force means it is acting in direction opposite to a already fixed direction, and negative potential energy means energy less than zero potential energy of a reference configuration.