The Work-Energy Principle states that the work done on an object is equal to the change in its kinetic energy. In simpler terms, when a force acts on an object and moves it, the energy transferred to the object changes its speed. This principle helps us understand how energy is transferred in various physical situations. For example, when you push a box across the floor, the work you do on the box increases its kinetic energy, making it move faster. Conversely, if friction slows the box down, the kinetic energy decreases, showing how work and energy are interconnected in motion.