Work, Energy and Power

Energy: Energy can neither be created nor destroyed. It comes in many forms: Kinetic Potential (gravitational, chemical, elastic) Nuclear Electric Solar

Work and Energy: If an object has energy, it can do work. Work produces energy.

Work: Work is done when a force moves an object through some distance. No work is done when the movement is at right angles to the force. (for instance no work is done walking with a heavy bag at a constant height because gravity is 90° to the distance the bag moves through)

Work:

Kinetic Energy: Kinetic energy velocity mass

Gravitational Potential: mass Potential energy gravity height

Elastic Potential: Also equal to the area under a F vs. x graph. Elastic potential Spring constant extension

Work and Power: A 60 Watt lightbulb uses 60 Joules of energy per second

Collisions As discussed, energy can be "lost" in many forms. Kinectic energy is not always conserved in a collision, one object might speed up, the other might slow down. In an elastic collision no kinetic energy is lost. In an inelastic collision energy is lost (to sound, heat, deformation etc.)

Elastic vs. Inelastic