Final answer:
Friction or deformation resulting from rubbing two surfaces together or striking metal with a hammer generates heat energy due to increased atomic and molecular motion, exemplifying the transformation of motion energy into heat energy.
Step-by-step explanation:
When you rub two surfaces together or strike a piece of metal with a hammer, the source of heat energy is the result of friction or deformation. These actions cause the atomic and molecular motion to increase, which results in the production of thermal energy. This can be particularly observed when materials in contact are rubbed vigorously, or when the metal deforms under the impact of a hammer, dispersing energy as heat. For instance, the heat produced during friction can be enough to melt ice when rubbed against a rough surface, or the heat from a struck piece of metal can make it warm to the touch.
The process of energy transformation is central to these examples. Motion energy is transformed into heat energy, exemplified by the warming of car brakes due to friction when they are used to slow down a vehicle. Another example of energy transformation occurs when a substance undergoes a chemical change, such as when gasoline combusts in a car engine, converting chemical energy into mechanical energy and heat.