Conservation of Energy

Conservation of Energy Energy can be neither created nor destroyed. It may only change forms.

Through the process of doing work, energy can move between the external world and the system.

When Work is Positive W is positive if external world does work on system and the energy of the system increases Example: When a spring is stretched, the work done by the stretching force is positive

When Work is Negative W is negative if the system does work on the external world and the energy of the system decreases Example: When brakes are applied on a moving vehicle, the work done by the breaking force is negative

Rube Goldberg Machine Ok go video How could the small push of a domino create all of that?

Ei = Ef Law of Conservation of Energy “Energy can be neither created nor destroyed. It may only change forms.” Ei = Ef Examples: A dropped object loses gravitational PE as it gains KE. A block slides across the floor and comes to a stop. A compressed spring shoots a ball into the air.

Conservation of Energy Problem Solving Ei = Ef What types of energy exist in the beginning? In the end? Kinetic: KE = ½ mv2 Gravitational Potential: PEg = mgh Elastic Potential: PEe = ½ kx2 Plug formulas in to each side of the equation (mass might cancel) Solve