Thermal Energy: The internal energy present in a system due to its temperature. It's like the "heat" used in our cafeteria analogy.
Industrial Revolution: A period from 1760 to 1840 where major changes in agriculture, manufacturing, mining, and transport had a profound effect on the socioeconomic and cultural conditions starting in the United Kingdom.
Mechanical Energy: The sum of potential energy and kinetic energy. It's what gets produced when our "cafeteria" cooks up its meal - or when a steam engine burns coal to produce motion.