Energy Notes

Energy

• Energy is the ability to do work or make things change.

• Energy occurs in two main types:– Potential• Gravitational, Chemical, Electrical, Nuclear, Elastic

– Kinetic• Electrical, Thermal, Light, Sound, Wind

Kinetic Energy

• Kinetic energy is energy of motion.– Only moving objects have kinetic energy

Kinetic Energy

• A person running has kinetic energy.

Potential Energy

• Potential energy is energy based on position, shape, or condition– Sometimes referred to as “stored” energy

Potential EnergyAn object on a high shelf has greater potential energy than one placed on a lower shelf.

A stretched elastic band has greater potential energy than one that isn’t stretched.

Large molecules, such as sugar, have greater potential energy than smaller molecules, such as carbon dioxide and water.

H20

CO2

SUGAR(C6H1206)

Energy Conversion

• To convert something is to change it into another form.

• Energy can be converted into different forms, but the amount of energy stays the same.– Law of Conservation of Energy: Energy cannot be

created or destroyed, only the form can change.

Potential to Kinetic Conversion

• Potential energy can be converted to kinetic energy.– Potential energy stored in a

battery can be converted to kinetic energy in an electric motor.

• The change happens the moment the object begins to move.

Kinetic to Potential Conversion• Kinetic energy can be converted to potential energy.– A windmill’s kinetic energy can be converted to potential

energy as it charges stored batteries.

Kinetic to Potential Conversion

• The transformation begins when the object enters a position with potential energy– A MOVING OBJECT MAY STILL HAVE POTENTIAL

ENERGY!!

Mechanical Systems

• A mechanical system is an arrangement of parts that work together.

• Simple mechanical systems use potential and kinetic energy – Roller coaster– Pendulum

Energy Conservation

• Energy is not lost or gained when it is transferred from potential to kinetic.– Energy is CONSERVED.

Mechanical Systems and Energy Conversion

Mechanical Systems and Energy Conversion

Energy Conservation

• As an object falls, potential energy decreases and kinetic energy increases.

Energy Conservation

• As an object is raised, potential energy increases and kinetic energy decreases.

Thermal Energy

• Energy can be transferred from place to place• Heat is given off when an object’s thermal

energy is transferred. – Conduction– Convection– Radiation

Conduction

• Conduction is the transfer of heat energy (thermal energy) by direct contact between particles.

Convection

• Convection is the transfer of heat energy (thermal energy) through liquids and gases by moving particles.

Radiation

• Radiation is the transfer of heat energy (thermal energy) by waves.

Thermal Energy