Dynamics - Work, energy and power — Energy

About this lesson

This unit introduces the concepts of kinetic energy, potential energy, and the principle of work and energy in dynamics. It defines kinetic energy as half the mass times the square of the velocity magnitude, and explains its units (Joule and Erg). The work-energy principle states that the change in kinetic energy equals the work done by the resultant force. Potential energy is defined as the work done by a constant force when moving a particle to a reference position, and the change in potential energy equals the negative of the work done by the force. The principle of conservation of energy is presented: the sum of kinetic and potential energies remains constant if no resistance acts. The unit also covers motion on rough inclined planes, where the change in potential energy equals the change in kinetic energy plus work done against resistances. Worked examples include projectiles, bullets penetrating barriers, bodies sliding on inclined planes, and a simple pendulum. Students learn to calculate kinetic and potential energies, apply the work-energy principle, and solve problems involving energy conservation and resistance.