kinetic energy,Potential energy,conservation of energy
In physics, the kinetic energy of an object is the energy which it possesses due to its motaion It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. in physics, potential energy is energy stored in a system of forcefully interacting physical entities. conservation of energy, principle of physics according to which the energy of interacting bodies or particles in a closed system remains constant. The first kind of energy to be recognized was kinetic energy , or energy of motion. In certain particle collisions, called elastic , the sum of the kinetic energy of the particles before collision is equal to the sum of the kinetic energy of the particles after collision. The notion of energy was progressively widened to include other forms.