Final answer:
If a person on a swing has 100% potential energy at the highest point, they have zero kinetic energy. As they swing downwards, potential energy is converted to kinetic energy, which is at its maximum at the lowest point, demonstrating the conservation of energy principle.
Step-by-step explanation:
When a person on a swing is at the highest point, all the energy in the system is potential energy, which means that at this point the kinetic energy is zero. As the person starts swinging downward, potential energy is converted to kinetic energy. At the bottom of the swing, the energy conversion is at its maximum and potential energy is at a minimum, indicating the kinetic energy is at its peak. This illustrates the principle of conservation of energy, which states that energy cannot be created or destroyed, only transformed from one form to another.
The pendulum model mentioned illustrates this energy transformation. At the highest point of a pendulum's swing, it has maximum potential energy and zero kinetic energy. As it swings downwards, potential energy decreases and kinetic energy increases, being greatest at the lowest point of the swing. This concept is purely theoretical in an ideal, frictionless environment as in real-world scenarios air resistance and friction will cause some energy to be lost as heat, and the swing won't reach the same height again without additional force being applied.
This principle also applies more broadly, for example, when a box falling off a shelf loses potential energy and gains kinetic energy as it descends, or when a baseball gains potential energy when hit into the air and loses kinetic energy as it climbs.