Final answer:
Mechanical energy is the sum of kinetic energy and potential energy, described by the equation KE + PE = constant. The conservation of mechanical energy in a closed system means that these energy forms can transform into each other without changing the system's total mechanical energy.
Step-by-step explanation:
Is mechanical energy the sum of kinetic energy and potential energy? Yes, mechanical energy is indeed the sum of kinetic energy (KE) and potential energy (PE). This is expressed as the equation KE + PE = constant. Mechanical energy, symbolized as EM, encompasses both kinetic energy, which is the energy of motion, and potential energy, which is the energy stored due to an object's position or arrangement. The potential energy can be specific to the context, such as gravitational potential energy or electric potential energy.
In a closed system, where no external forces act to add or remove energy, the Law of Conservation of Mechanical Energy states that the total mechanical energy remains constant. This means that a loss of potential energy corresponds to an equivalent gain in kinetic energy and vice versa.
For instance, a swinging pendulum at its highest point has maximum potential energy and minimal kinetic energy. As it swings downward, potential energy is converted into kinetic energy, increasing the pendulum's speed. At the lowest point of its swing, the pendulum has maximum kinetic energy and minimum potential energy. If there are no dissipative forces like air resistance, the sum of the kinetic and potential energy—the mechanical energy—would remain constant throughout the motion.