* Kinetic Energy: Particles are constantly in motion, even in solids. This motion is called kinetic energy. The more kinetic energy a particle has, the faster it moves.

* Temperature: Temperature is a measure of the average kinetic energy of the particles in a substance. Higher temperatures mean particles move faster.

* Forces: Particles are attracted to each other by forces, like the electromagnetic force. To move, particles need to overcome these forces. This requires energy.

Examples:

* Heating a substance: When you heat a substance, you increase the kinetic energy of its particles, causing them to move faster.

* Diffusion: Particles move from areas of high concentration to low concentration because the random motion of the particles leads them to spread out. This movement requires energy.

* Phase Changes: Changes in state of matter (solid to liquid to gas) require energy to overcome the attractive forces between particles and allow them to move more freely.

In summary: Particles require energy to move because they need to overcome attractive forces and increase their kinetic energy. This energy can come from heat, chemical reactions, or other sources.