Conservative and Nonconservative Forces F is conservative if: The work done by the force on on object moving from one point to another depends only or the initial old final positions and is independent of The path taken.

A force that’s not a conservative is called a nonconservative force.

POTENTIAL ENERGY Energy associated with forces that depend on position or configuration of objects relative to the surroundings. Gravitational Potential Energy Elastic Potential Energy If configuration changes potential energy changes.

Work and Potential Energy Work-Energy principle Q: Similar relation between work and potential energy?

Gravitational Potential Energy

Potential energy changes for or roller coaster A 1000 kg roller coaster car moves from point A to point B and then point C. Determine potential energy changes when car goes to point B and point C.

Elastic Potential Energy

Conservation of Mechanical Energy The Mechanical Energy Em of a system is the sum of its potential energy U and kinetic energy K. Assume only conservative forces cause energy transfer Assume the system is isolated - no external force from outside causes energy transfer Total Mechanical Energy is Conserved

Energy Conservation with Dissipative Forces Conservation of mechanical energy (no friction) Assume the body moving is subject to friction forces

Gravitational Potential Energy

POWER Power is defined as the rate at which the work is done. Whenever a work is done, energy is transferred. Power is the rate at which energy is transformed.