Energy

May 6- May 22ENERGY

Energy- The ability to do work Kinetic Energy- The energy of motion Potential Energy- Energy stored as a result of position or

shape Gravitational Potential Energy- Potential energy that

depends on an object’s height above a reference point Elastic Potential Energy- The potential energy of an

object that is stretched or compressed Mechanical energy- Energy associated with the motion

and position of everyday objects Thermal Energy- The total potential and kinetic energy

related to the motion of all particles in an object Chemical Energy- The energy stored in chemical bonds Electromagnetic Energy- a form of energy consisting of

changing electric and magnetic fields Nuclear Energy- The energy stored in the nuclei of atoms

WHAT IS ENERGY?

In 1845, James Prescott Joule published results from a series of well constructed experiments and concluded three “laws of thermodynamics”

The 1st law of Thermodynamics- Energy cannot be created or destroyed When we observe an energy transformation, all amounts of

energy must be accounted forThe 2nd law of Thermodynamics- Energy fl ows from high

concentration to low concentration. (Always from hot objects to cold objects. When we observe an energy transformation, energy is always

“lost” due to things like friction, sound, and heatThe 3 rd law of Thermodynamics- All objects contain

some amount of thermal energy measured on the Kelvin Scale. Zero degrees Kelvin cannot ever be reached. All objects have thermal energy that can be measured and

accounted for

THERMODYNAMICS

It is important to recognize our perception of energy transformation vs. reality of energy transformation. Example, touch your table top with one hand and the

metal bar with the other hand. Which surface is colder? Both surfaces are the same temperature, why does one

FEEL colder?You rub your hands together and they get warm?You eat a good breakfast before you take your final

exams?You start your car and drive to the store?You fl ip on the lights when you walk into class?You create a camp fi re to roast marshmallows?The alternator in your car uses the movement of your

car’s engine to charge the battery?

ENERGY TRANSFORMATION

HALF PIPE SCIENCE

Kinetic Energy = Potential Energy =

HALF PIPE SCIENCE

Kinetic Energy = Potential Energy =

HALF PIPE SCIENCE

Kinetic Energy = Potential Energy =

HALF PIPE SCIENCE

Kinetic Energy = Potential Energy =

HALF PIPE SCIENCE

Kinetic Energy = Potential Energy =

Electricity- The fl ow of electrons in a sample Conductor- Physical property of matter which allows

electrons to move freely through it. Insulator- Physical property of matter which does not allow

electrons to move freely through it. Electric current- The rate at which charge passes a given

point The rate of flow of electrons in a sample is its current The unit for current is “Ampere” (A), called amp for short

Voltage- The diff erence in energy per unit charge as a charge moves between two points in the path of a current. The unit for voltage is the “Volt” (V)

Resistance- The opposition to the fl ow of electric charge The unit for resistance is the “ohm” (R, or Ω) Can be thought of as “Electrical Friction”

ELECTRICITY

Georg Ohm discovered that current, voltage, and resistance are all interrelated. He hypothesized that…

Amperes (A) = volts (V) / ohms (Ω) I (current) = V / R

OHM’S LAW

Electric Power- the rate at which electrical energy is used to do work. The unit for electrical power is “Watt” (W)

Power = Voltage x Current (P=VxI)

ELECTRIC POWER

Electrical Energy- a measurement of power used with the time that it is used The unit is Kilowatt-hour (KWH)

Electrical Energy = power (kW) x time (h)KWH = kW x h

ELECTRICAL ENERGY