# Force Force can more broadly be defined as: > Any interaction that changes the motion of an object. **Force** is a vector that describes the interaction between objects that tends to change the motion of an object. In a classical mechanics context, force is absolutely the easiest to think about in terms of what it is literally defined as: $F = ma$ So say we are given a system, say a ball on a hill. We know it's mass, $m$. And, we know how it's velocity is changing, hence we know $a$. That perfectly provides us with $F$, the force. ### Conservative Forces $F = - \frac{dU}{dx}$ The negative sign indicates that the force acts in the direction of decreasing potential energy. This is a fundamental nature of conservative forces: they always act to minimize the potential energy of a system. --- Date: 20240519 Links to: Tags: References: * []()