A child is pushing a wagon up a hill. The wagon gains energy as it moves up the hill. According to the law of conservation of energy, energy is never created nor destroyed. But the wagon just gained energy! Does this scenario break law of conservation of energy? Explain why or why not.
The correct answer and explanation is:
The law of conservation of energy states that energy cannot be created or destroyed; it can only be transformed from one form to another. In this case, the child pushing the wagon up the hill does not violate this principle.
When the child pushes the wagon, they are applying a force that works against gravity. The work done by the child (the force applied over the distance moved) is transferred to the wagon as potential energy. Potential energy is the energy stored in an object due to its position, and in this case, the wagon gains potential energy as it moves up the hill.
Even though the wagon gains energy, it does not mean that energy was created. The child’s muscular energy is being converted into mechanical energy, which is then transferred to the wagon. This mechanical energy is what causes the wagon to gain potential energy. In essence, the energy the wagon gains comes from the child’s energy, not from nowhere.
If the child stops pushing the wagon, the wagon will eventually lose this potential energy and convert it back into kinetic energy as it moves down the hill, demonstrating the principle of energy conservation. This energy is just moving between different forms, but the total amount of energy remains constant.
Thus, this scenario adheres to the law of conservation of energy. The energy is not created but transferred and transformed from one object (the child) to another (the wagon), maintaining the overall balance of energy in the system.