Question

analyze how each of the three actions in the table increases the kinetic, potential, or total thermal energy of a substance.
actions that increase thermal energy explanation
raise the temperature of the object
pull atoms or molecules that attract one another farther apart
add mass to the object, without changing its temperature

Explanation:

• When the temperature of an object is raised, the average kinetic energy of its particles increases. Since thermal energy is the sum of the kinetic and potential energies of the particles in a substance, raising the temperature increases the kinetic energy and thus the total thermal energy of the substance.
• When atoms or molecules that attract one another are pulled farther apart, work is done against the attractive forces between them. This increases the potential energy of the particles. As thermal energy is the sum of kinetic and potential energies, this action increases the potential energy and thus the total thermal energy of the substance.
• When mass is added to an object without changing its temperature, the number of particles in the substance increases. Since thermal energy depends on the number of particles (as well as their kinetic and potential energies), adding mass (more particles) increases the total thermal energy of the substance. The kinetic energy per particle (related to temperature) remains the same, but the total kinetic energy (since there are more particles) and the total potential energy (more particles can have more potential energy depending on their arrangement) contribute to an increase in total thermal energy.

Answer:

• Raise the temperature of the object: Increases kinetic energy (and total thermal energy).
• Pull atoms or molecules that attract one another farther apart: Increases potential energy (and total thermal energy).
• Add mass to the object, without changing its temperature: Increases total thermal energy (more particles mean more total kinetic and potential energy contributions).