Final answer:
Particles that make up matter move at all speeds and in all directions, a concept described by velocity and pertinent to understanding momentum in physics.
Step-by-step explanation:
The particles that make up matter move at all speeds and in all directions. Matter is constantly in motion, whether it is the rapid movement of particles in a gas or the vibrations of atoms in a solid. In physics, we describe this motion in terms of the particles' velocity, which includes both speed and direction. The mass of the particles combined with their velocity is referred to as momentum. When discussing motion, we need to consider these properties to understand the behaviors of different materials under various conditions.