Energy Flashcards
(13 cards)
Energy
Energy is the capacity to do mechanical work; the higher the energy content the greater the impact when it is transformed or transferred. It is a measure of an object’s ability to so work, symbolized by E and J.
Law of Conservation of Energy
Energy in any closed system is conserved. Cannot be created, but can be transferred or transformed.
Energy changes
When energy transformations occur within a closed system: Change in E = Final E - Initial E. When there is a change in energy, work has been performed, where change in E = W.
Mechanical Work
Work was defined as a change in energy, but each energy type can be defined by its own unique mechanical equation. Work (J) = Force (N) x Displacement (m)
Force Displacement Graph
The worked performed by an object can be determined from a force-displacement graph. The area under the curve is equal to the work performed.
Mechanical Work
Mechanical Work is the transfer of energy to or from an object by the action of a force over a distance. The total mehcnical energy of a system can be found adding the KE and PE. IF these two types of energies undergo change, then mechanical work is performed. The mechanical work of such transformations is equal to the change in mechanical energy. W = DeltaE
Law of Conservation of Mechanical Energy
When mechanical energy is conserved by the transformation of GPE to KE or KE to GPE: KE1 + PE1 = KE2 + PE2
Kinetic energy
Energy of motion: 1/2mv^2
Conserving Mechanical Energy
Kinetic Energy1 + Potential Energy1 = Kinetic Energy1 + Potential Energy2
Power
Power is how quickly work is performed
Interpreting Energy-Time
At power is the rate at which work is performed, it is the change in energy over time. The gradient in a change in energy vs change in time graph is power.
Elastic Collisions
Elastic collisions have momentum and kinetic energy conserved. No net change in the sum of the kinetic energies of the objects involved and no net change to the sum of the momenta of the objects involved.
Inelastic Collisions
Inelastic collisions are collisions where kinetic energy is not conserved. Momentum is conserved in all collisions, even in inelastic ones.
