What is Kinetic Energy?
Deriving Kinetic EnergyKinetic energy is closely linked with the concept of work, which is the scalar product(or dot product) of force and the displacement vector over which the force is applied.
v = v + 2asThe kinetic energy, K (or sometimes E) is, therefore, defined as:
It should be noted that, as mentioned before, this quantity will always be a non-zeroscalar quantity. If the object has mass and is moving, it will always be positive. It will be zero in the case of a massless object or an object at rest (zero velocity). Thekinetic energy equation, therefore, gives us no information about the direction of the motion, only about the speed.
Work-Energy TheoremThe work-energy theorem comes from the above derivation, and indicates that the work done by an external force on a particle is equal to the change in kinetic energy of the particle. Mathematically, then, you get:
W = K - K = delta-K