The Nature of The Nature of EnergyEnergy

Section 4.1Section 4.1

EnergyEnergy

Every change that occurs involves Every change that occurs involves ..

Moving objects have energyMoving objects have energy You can tell an object has energy when it: You can tell an object has energy when it:

Changes its environmentChanges its environment Changes itselfChanges itself

EnergyEnergy Electrical – moving electronsElectrical – moving electrons Chemical – from bondsChemical – from bonds Thermal- heatThermal- heat

EnergyEnergy

Energy exists in many different formsEnergy exists in many different forms It may look different, but it’s still energy. It may look different, but it’s still energy.

Examples: fire, movement, gasoline in a bucketExamples: fire, movement, gasoline in a bucket Kinetic energy- energy in the form of Kinetic energy- energy in the form of

motionmotion Depends on mass and velocity of an objectDepends on mass and velocity of an object Increase in either mass or velocity = Increase in either mass or velocity =

increase in energyincrease in energy KE =1/2 mvKE =1/2 mv22

Units = kg*m/s Units = kg*m/s

Types of EnergyTypes of Energy

KE = ½ mvKE = ½ mv22 Velocity changes will Velocity changes will impact KE more because velocity is impact KE more because velocity is squared.squared.

Potential Energy – energy of positionPotential Energy – energy of position Energy in stationary objects and bondsEnergy in stationary objects and bonds

Elastic Potential Energy – Energy of Elastic Potential Energy – Energy of compression or stretchingcompression or stretching

Chemical Potential Energy – Energy Chemical Potential Energy – Energy stored in bondsstored in bonds Gasoline, food, hand warmersGasoline, food, hand warmers

Types of EnergyTypes of Energy Gravitational Potential Energy- Energy Gravitational Potential Energy- Energy

stored due to position above the surface of stored due to position above the surface of EarthEarth Depends on mass of object, height of object Depends on mass of object, height of object

above ground, and acceleration due to gravityabove ground, and acceleration due to gravity GPE = m x h x g g = acceleration due to GPE = m x h x g g = acceleration due to

gravitygravity All energy – measured in units of Joules All energy – measured in units of Joules

1 J = 1 kgm1 J = 1 kgm22/ s/ s22

Energy can be converted: Energy can be converted: As an object falls, GPE decreases and KE As an object falls, GPE decreases and KE

increasesincreases