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Review: PE & KE Potential Energy – “stored” E Kinetic Energy – energy of motion / “released” E
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Unit 5 – Lecture 2
Review: PE & KEPotential Energy – “stored” E Kinetic Energy – energy of motion /
“released” E
Conservation of EnergyLaw of Conservation of Energy:
energy can neither becreated nor destroyed in normal reactions
energy can be changed in form from one to another
initial energy = final energyenergy in = energy outaka 1st law of thermodynamics
Mechanical EnergyMechanical E – total amount of PE & KE in a
systemas PE decreases, KE increasesas PE increases, KE decreaseswhat kind of relationship is this…direct or
inverse?
Mechanical EnergyEquation:MEinitial = MEfinal
(PE + KE)initial = (PE + KE)final (m g h + ½ m v2 )initial = (m g h + ½ m v2 )final
Mechanical EnergyME in a pendulum:
PracticeAt which point…is GPE at a maximum?
why?is KE at a maximum?
why?
Practice Which of these describes E? [any]Ability to do work Ability to cause changeAbility to increase energy Ability to decrease
work
Joules is NOT a unit for which of these?PE KEForce Work
Forms of EnergyMechanical Energy
energy of an object due to its motion [kinetic E] or position [potential E]
Forms of EnergyElectromagnetic E
waves of mostly invisible E
light energy often is converted into thermal E
can be converted into chemical E through photosynthesis
Forms of EnergyChemical E
stored and released in the bonds between atoms
food, batteries
Forms of EnergyNuclear E
stored and released from the nucleus of an atom
Forms of EnergyThermal E
heat in all its forms and flows
recall – exothermic & endothermic
transferred through conduction, convection, & radiation
Forms of EnergyElectrical E
separation and movement of electrons[not really a form of E
on its own – it is a combination of forms of Mechanical and Electromagnetic E]
PracticeWhen you are watching tv, what energy
conversions are taking place?Which energy transformation takes place
when a match is struck against the side of a matchbox and bursts into flames?
What causes you to hear something? What kind of energy is sound?