Answer: Energy for moving objects comes from the system that sets the motion in the first place. When an object moves, its energy is drawn from the object’s energy stores and transformed into kinetic energy as it gains speed, or vice versa as it loses speed. The primary sources depend on the situation, but the common idea is that energy is transferred from a source (like a motor, a falling mass, a stretched spring, gravitational field, electrical energy, etc.) into the object's motion. Key ideas
- Kinetic energy increases when an object speeds up, drawing energy from a cause such as a propulsion force or gravity. This energy transfer reduces the source’s energy or changes its state accordingly, while the moving object’s kinetic energy grows.
- Potential energy can be converted into kinetic energy. For example, a roller coaster car at the top of a hill has high gravitational potential energy; as it descends, that potential energy converts into kinetic energy, accelerating the car.
- In a closed system, the total mechanical energy (the sum of kinetic and potential energies) can be redistributed without changing the total, though non-ideal effects like friction convert some mechanical energy into other forms such as heat.
If you want, I can tailor this to a specific scenario (e.g., a car accelerating, a pendulum, or a mass-spring system) and walk through the energy transfers step by step.
