Energy ALL ENERGY has the ABILITY to do WORK!! Like WORK, ENERGY will be MEASURED in JOULES (J)

EnergyEnergy

ALL ENERGY ALL ENERGY has the has the ABILITY to do WORK!!ABILITY to do WORK!!

Like WORK , Like WORK , ENERGYENERGY will be will be MEASURED in MEASURED in JOULES (J)JOULES (J)

How is all energy divided?How is all energy divided?

PotentialEnergy

KineticEnergy

All Energy

GravitationPotentialEnergy

ElasticPotentialEnergy

ChemicalPotentialEnergy

What is Potential Energy?What is Potential Energy?

o Energy that is Energy that is stored and waiting stored and waiting to be used laterto be used later

Potential EnergyPotential EnergyThe energy that an object has because of the position, The energy that an object has because of the position, shape, or condition of the object is called shape, or condition of the object is called potential potential energy.energy.

Potential energy is stored in many ways.Potential energy is stored in many ways.

• Elastic potential energyElastic potential energy is the energy stored in any type of is the energy stored in any type of stretched or compressed elastic material, such as a spring stretched or compressed elastic material, such as a spring or a rubber band.or a rubber band.

• Gravitational potential energyGravitational potential energy is the energy stored in the is the energy stored in the gravitational field which exists between any two or more gravitational field which exists between any two or more objects.objects.

• Chemical potential energy Chemical potential energy is energy stored in a compound is energy stored in a compound or element that can be released during a chemical change.or element that can be released during a chemical change.

What is Gravitational Potential What is Gravitational Potential Energy?Energy?

o Potential energy Potential energy due to an object’s due to an object’s positionposition

o P.E. = mass xP.E. = mass x height x height x

gravitygravity

Don’t look down, Rover!

Good boy!

Potential EnergyPotential Energy

Gravitational potential energy depends on both Gravitational potential energy depends on both mass and height.mass and height.

Gravitational Potential Energy EquationGravitational Potential Energy Equationgrav. PE = mass grav. PE = mass free-fall acceleration free-fall acceleration height height

EEpgpg = mgh = mgh units kg units kg * * m/sm/s22 x mx m or or

JoulesJoules

The height can be relative.The height can be relative.• The height used in the above equation is usually The height used in the above equation is usually

measured from the ground. measured from the ground.

• However, it can be a relative height between two However, it can be a relative height between two points, such as between two branches in a tree.points, such as between two branches in a tree.

What is Elastic Potential What is Elastic Potential Energy?Energy?

o Potential energy due compression Potential energy due compression or expansion of an elastic object.or expansion of an elastic object.

Notice the ball compressingand expanding

Potential EnergyPotential Energy

Elastic potential energy depends on the Elastic potential energy depends on the distance an object can be compressed or distance an object can be compressed or stretched. stretched.

Elastic Potential Energy EquationElastic Potential Energy Equationelas. PE = ½ x spring constant elas. PE = ½ x spring constant (stretch distance) (stretch distance)22

EEss = ½ kd = ½ kd22 units N/m x units N/m x mm2 2 or Joules (J)or Joules (J)

The spring constant (k) The spring constant (k) • Is determined by measuring the force needed to Is determined by measuring the force needed to

stretch or compress a spring.stretch or compress a spring.

k = Force/distance k = Force/distance units N/m units N/m

What is Chemical Potential What is Chemical Potential Energy?Energy?

o Potential energy Potential energy stored within the stored within the chemical bonds chemical bonds of an objectof an object

What is Kinetic Energy?What is Kinetic Energy?

o Energy an object has Energy an object has due to its motiondue to its motion

o K.E. = .5(mass x K.E. = .5(mass x speedspeed22))

Kinetic EnergyKinetic Energy

The energy of a moving object due to the The energy of a moving object due to the object’s motion is called object’s motion is called kinetic energy.kinetic energy.

Kinetic energy depends on mass and Kinetic energy depends on mass and speed.speed.Kinetic Energy EquationKinetic Energy Equation

kinetic energy 1

2mass speed squared

KE 1

2mv 2

• Kinetic energy depends on speed more than mass.

units kg * m2/s2 or J

Using you book Using you book

Complete practice problems 1-4 & 1-3Complete practice problems 1-4 & 1-3

From pages 393 & 395From pages 393 & 395