* Burning wood: The chemical energy stored in the wood is transformed into heat and light energy. The total amount of energy remains the same, but its form changes.
* A car engine: The chemical energy in gasoline is converted into mechanical energy that moves the car. Some energy is lost as heat due to friction, but the total energy remains constant.
* Solar panels: Sunlight (radiant energy) is converted into electrical energy. The total energy remains the same, but its form changes.
* A hydroelectric dam: The potential energy of water stored at a high elevation is converted into kinetic energy as the water flows down and then into electrical energy by a turbine. The total energy remains the same.
* A pendulum swinging: The pendulum continuously converts potential energy into kinetic energy and vice versa. The total energy of the system (potential + kinetic) remains constant, ignoring losses due to friction.
Essentially, any process involving energy transfer or transformation exemplifies the first law of thermodynamics.
