How do we know that the energy of an object or system has changed?
Energy is all around us and can be detected using our senses. We can feel heat, see light, hear sound, and see movement. This is evidence that energy is present and changing. Energy changes in a system can be represented with a system diagram that shows the components of the system, the observable changes taking place, where in the system energy changes are occurring, where the energy comes from, and where the energy goes.
