Unit 9Unit 9EnergyEnergy

TopicsTopics

What is energy?What is energy?

Types of energyTypes of energy

EquationsEquations

Thermodynamic Laws and “lost” energyThermodynamic Laws and “lost” energy

What is Energy?What is Energy?

What is your definition of energy? Write it What is your definition of energy? Write it downdown

Does this have energy?Does this have energy?

Energy – the Energy – the ability ability to do workto do work

Units of energy – joules, British Thermal Units Units of energy – joules, British Thermal Units (BTUs), calories, Kilowatt-hour(BTUs), calories, Kilowatt-hour

S.I. Unit - S.I. Unit - JoulesJoules

Forms of energyForms of energy

All energy can be broken down into 2 All energy can be broken down into 2 categoriescategories

1. Kinetic 1. Kinetic

– – the energy of motionthe energy of motion

2. Potential2. Potential

– – stored energystored energy

Kinetic EnergyKinetic Energy

Which has more kinetic energy?Which has more kinetic energy?

Kinetic energy depends on:Kinetic energy depends on:

SPEED!SPEED!

Equation:Equation:

KE = ½ mvKE = ½ mv22

Kinetic EnergyKinetic Energy

Types:Types:

Heat – the general motion of atomsHeat – the general motion of atoms

Electricity – movement of electrons Electricity – movement of electrons

Any other movement!Any other movement!

Dissipated EnergyDissipated Energy

Can he roll forever with one push?Can he roll forever with one push?

What happens to the energy he puts in?What happens to the energy he puts in?

It gets transformed into It gets transformed into heat/sound/deformationheat/sound/deformation/etc./etc.

We call this We call this lost / unusable / internal / lost / unusable / internal / dissipated energydissipated energy

It is a form of kinetic energyIt is a form of kinetic energy

It constantly grows over time!It constantly grows over time!

Dissipated EnergyDissipated Energy

Why does energy become unusable?Why does energy become unusable?

This relates back to chemistry class:This relates back to chemistry class:

22ndnd law of Thermodynamics: law of Thermodynamics:

entropy always increasesentropy always increases

this means whatever “usable” energy you this means whatever “usable” energy you start with is constantly being converted into start with is constantly being converted into “unusable” energies which cannot be “unusable” energies which cannot be converted backconverted back

Potential EnergyPotential Energy

This is a general term for any energy that is This is a general term for any energy that is storedstored

Types:Types:

Gravitational Kinetic Energy (GPE) Gravitational Kinetic Energy (GPE) – energy – energy stored based on its position in a gravitational fieldstored based on its position in a gravitational field

the higher an object, the more GPEthe higher an object, the more GPE

EQUATIONEQUATION

GPE = m*g*hGPE = m*g*h

Potential EnergyPotential Energy

Chemical Potential Energy (CPE) – energy Chemical Potential Energy (CPE) – energy stored between bonds of moleculesstored between bonds of molecules

Examples) sugars from photosynthesis, fuel, Examples) sugars from photosynthesis, fuel, foodfood

burning fuel or metabolizing food is the burning fuel or metabolizing food is the process of releasing the energy from the process of releasing the energy from the bondsbonds

Potential EnergyPotential Energy

Nuclear Potential Energy (NPE) – energy Nuclear Potential Energy (NPE) – energy stored stored withinwithin an atom an atom

Future: use equations to calculate how much Future: use equations to calculate how much energy exists in a situationenergy exists in a situation

Learn how energy relates to workLearn how energy relates to work

How does power fit in?How does power fit in?