Potential energy is stored energy until it is allowed to move, then it becomes __________.

• A. Mechanical energy
• B. Kinetic energy
• C. Thermal energy
• D. Potential energy

Answer: (B)

Potential energy is energy stored by position. When that energy is released, it becomes energy of motion. So the energy immediately after release is kinetic energy, which depends on how fast the object is moving (1/2 mv^2). In a gravity example, a ball at height has potential energy; as it falls, that energy converts to kinetic energy, and if no energy is lost to friction, the total mechanical energy (potential plus kinetic) remains constant. At the lowest point, the kinetic energy is at its maximum while the potential energy is at its minimum. Mechanical energy is the sum of both forms, and thermal energy would arise from energy lost to friction, not the immediate result of release.