Ch.9, Sec.1 – What Is Energy?Ch.9, Sec.1 – What Is Energy?

energyenergy: the capacity to do work: the capacity to do work

Energy and Work: Working TogetherEnergy and Work: Working Together

- work is done when a force causes an object to move in work is done when a force causes an object to move in the direction of the forcethe direction of the force

- when one object does work on another, energy is when one object does work on another, energy is transferred from the 1st object to the 2ndtransferred from the 1st object to the 2nd

- therefore, work is a therefore, work is a transfertransfer of energy! of energy!

- energy is expressed in units of Joules (J)energy is expressed in units of Joules (J)

- all matter has atoms; therefore, - all matter has atoms; therefore, all matter has energyall matter has energy!!!!!!!!!!

Ch.9, Sec.1 – What Is Energy?Ch.9, Sec.1 – What Is Energy?

Kinetic EnergyKinetic Energy

kinetic energykinetic energy: the energy of motion: the energy of motion

- all moving objects have kinetic energy & this energy can all moving objects have kinetic energy & this energy can be used to do workbe used to do work

- kinetic energy can be found using the following formula:kinetic energy can be found using the following formula: KE = KE = mvmv²² 22 - m- m stands for mass in kilograms, stands for mass in kilograms, vv stands for the objects stands for the objects speed (the more speed & mass of an object means greater speed (the more speed & mass of an object means greater kinetic energy) kinetic energy)

- speed has a greater effect on kinetic energy than mass speed has a greater effect on kinetic energy than mass (faster cars cause greater crashes)(faster cars cause greater crashes)

Ch.9, Sec.1 – What Is Energy?Ch.9, Sec.1 – What Is Energy?

Potential EnergyPotential Energy

potential energypotential energy: the energy that an object has because of : the energy that an object has because of the position, shape, or condition of the objectthe position, shape, or condition of the object

- any object elevated from the ground has gravitational any object elevated from the ground has gravitational potential energy (the more weight & height means greater potential energy (the more weight & height means greater GPE)GPE)

- gravitational potential energy can be found using the - gravitational potential energy can be found using the following formula:following formula:

GPE = weight x height GPE = weight x height

- GPE is expressed using Newton-metersGPE is expressed using Newton-meters

- height of GPE is a measure of how far an object has to fallheight of GPE is a measure of how far an object has to fall

Ch.9, Sec.1 – What Is Energy?Ch.9, Sec.1 – What Is Energy?

Mechanical EnergyMechanical Energy

mechanical energymechanical energy: the total energy of motion and position of : the total energy of motion and position of an object (can be all potential, all kinetic, or some of each) an object (can be all potential, all kinetic, or some of each)

- mechanical energy can be found using the following mechanical energy can be found using the following formula:formula: ME = PE + KEME = PE + KE

- mechanical energy remains the same unless it transfers mechanical energy remains the same unless it transfers some of its energy to another objectsome of its energy to another object

- even if mechanical energy stays the same, potential or even if mechanical energy stays the same, potential or kinetic energy can increase or decreasekinetic energy can increase or decrease

Ch.9, Sec.1 – What Is Energy?Ch.9, Sec.1 – What Is Energy?

Other Forms of EnergyOther Forms of Energy

thermal energythermal energy: all of the : all of the kinetic energy due to kinetic energy due to random motion of the random motion of the particles that make up an particles that make up an object object

- there’s more kinetic there’s more kinetic energy in gases than solids energy in gases than solids because of the molecular because of the molecular movementmovement

Ch.9, Sec.1 – What Is Energy?Ch.9, Sec.1 – What Is Energy?

chemical energychemical energy: the : the energy of a compound that energy of a compound that changes as its atoms are changes as its atoms are rearranged rearranged

- chemical energy is a - chemical energy is a form of potential energy form of potential energy because it depends on because it depends on the position & the position & arrangement of the arrangement of the atoms in the compound atoms in the compound

Ch.9, Sec.1 – What Is Energy?Ch.9, Sec.1 – What Is Energy?

electrical energyelectrical energy: the energy : the energy of moving electrons of moving electrons

- changing positions of - changing positions of magnets at power plants magnets at power plants provides electrical provides electrical energy (potential energy energy (potential energy too) too)

Ch.9, Sec.1 – What Is Energy?Ch.9, Sec.1 – What Is Energy?

sound energysound energy: the energy : the energy caused by an object’s caused by an object’s vibrations (potential energy vibrations (potential energy turned into kinetic energy) turned into kinetic energy)

light energylight energy: energy produced : energy produced by the vibrations of electrically by the vibrations of electrically charged particles charged particles

- light energy can travel light energy can travel through a vacuum! (an area through a vacuum! (an area with little or no atoms, like with little or no atoms, like deep space)deep space)

Ch.9, Sec.1 – What Is Energy?Ch.9, Sec.1 – What Is Energy?

nuclear energynuclear energy: the energy : the energy that comes from changes in that comes from changes in the nucleus of an atom the nucleus of an atom

- energy can be from energy can be from fusionfusion where atoms can join together to where atoms can join together to create electrical energy (Sun)create electrical energy (Sun)

- energy can be from - energy can be from fissionfission where atoms can be split where atoms can be split apart in the nucleus to create apart in the nucleus to create a lot of potential energy a lot of potential energy (uranium in the atomic (uranium in the atomic bombs) bombs)