Here's why sometimes we might talk about force as a quantity in general:
* Shortened language: In everyday language, we often simplify our descriptions. We might say "the force of gravity" or "the force of friction" without specifying the direction. This is because the context usually implies the direction.
* Focus on magnitude: In some situations, we might be primarily interested in the strength of the force, not its precise direction. For example, we might talk about the "force of the engine" without worrying about the exact direction of the car's motion.
It's important to remember that, technically, force is a vector quantity and always has both magnitude and direction. Even when we're only interested in one aspect, the other aspect is still present.
