Final answer:
Temperature measures the average kinetic energy of moving particles in a substance; the faster these particles move, the higher the temperature. Kinetic energy increases with particle velocity, and thus, so does the temperature. Absolute zero represents the temperature at which particles would theoretically stop moving.
Step-by-step explanation:
The measurement of the average kinetic energy (energy of movement) of particles in a volume is temperature. The faster the particles are moving, the higher the temperature. Kinetic energy is the energy of motion, and it increases in proportion to velocity squared. Therefore, when the atoms and molecules in an object are moving or vibrating quickly, they have a higher average kinetic energy, and we say that the object is "hot". Conversely, when atoms and molecules move slowly, they have lower average kinetic energy, indicating the object is "cold". As per the kinetic-molecular theory, the temperature of a substance is directly proportional to the average kinetic energy of its particles.
With an increase in temperature, particles move faster because their kinetic energy increases. This is why chemical reactions, for example, tend to occur at a faster rate at higher temperatures. Finally, absolute zero is theoretically the lowest possible temperature, where particles would have minimal vibrational motion, signifying the absence of thermal energy.