Rest kinetic energy is zero. An object at rest has no kinetic energy. Kinetic energy is the energy of motion, and if there's no motion, there's no kinetic energy. This is a fundamental principle of physics.
Understanding Kinetic Energy
Kinetic energy (KE) is the energy possessed by an object due to its motion. It's calculated using the formula: KE = 1/2 * mv², where 'm' is the mass and 'v' is the velocity of the object. When an object is stationary (v = 0), its kinetic energy is automatically zero, regardless of its mass.
Rest Energy vs. Kinetic Energy
It's crucial to distinguish between rest energy and kinetic energy. Rest energy (E₀ = mc²) is the energy an object possesses due to its mass, even when it's at rest. This concept is central to Einstein's theory of special relativity. Kinetic energy is the additional energy an object gains due to its motion. The total energy of an object is the sum of its rest energy and its kinetic energy.
Example: A stationary baseball has rest energy (based on its mass), but its kinetic energy is zero. Once thrown, it gains kinetic energy, and its total energy increases.
Several sources confirm this understanding:
- “[W]hen an object is at rest, its kinetic energy is zero.” This directly states that an object at rest has no kinetic energy.
- Physics Stack Exchange discussions about rest energy and kinetic energy emphasize that the total energy minus the rest energy equals the kinetic energy. If the object is at rest, there is no kinetic energy to subtract.
- Various online problem sets and solutions confirm the calculation of kinetic energy involves velocity; therefore, a zero velocity leads to zero kinetic energy.
