Chapter 4-IPSChapter 4-IPS

Anything that causes change requires Anything that causes change requires energy. Energy=the ability to cause energy. Energy=the ability to cause change.change.

Energy comes in different forms:Energy comes in different forms: electricalelectrical chemical (ex. Stored in food or in chem chemical (ex. Stored in food or in chem

bonds)bonds) radiant (sunlight)radiant (sunlight) thermal (heat)thermal (heat)

Kinetic EnergyKinetic Energy

Energy in the form of motionEnergy in the form of motion The amount of KE depends on the The amount of KE depends on the

obj’s mass and speed.obj’s mass and speed. Formula: 1/2mass x speedFormula: 1/2mass x speed22

unit for KE =Joule (J)unit for KE =Joule (J)

Potential EnergyPotential Energy Stored energy in a motionless Stored energy in a motionless

object, giving it the potential to object, giving it the potential to change.change. Elastic PEElastic PE- energy stored in things that - energy stored in things that

stretch or compressstretch or compress Chemical PEChemical PE- energy stored in chem. - energy stored in chem.

bonds (food)bonds (food) Gravitational PEGravitational PE- energy stored in - energy stored in

things that are above the Earth.things that are above the Earth. The amount of GPE depends on the mass, The amount of GPE depends on the mass,

acceleration due to gravity and the height acceleration due to gravity and the height above the groundabove the ground

GPE= mass (kg) x 9.8m/sGPE= mass (kg) x 9.8m/s22 x height x height (m)(m)

4-24-2

Energy conversions-energy changing Energy conversions-energy changing from one form to another.from one form to another.

Mechanical Energy= total of Mechanical Energy= total of potential and kinetic energy in a potential and kinetic energy in a system. (ME=KE+PE)system. (ME=KE+PE)

Law of Conservation of Law of Conservation of EnergyEnergy

Energy may change from one form Energy may change from one form to another but the total amount of to another but the total amount of energy never changes.energy never changes.

Ex) as a swing moves back and Ex) as a swing moves back and forth, its energy converts from KE forth, its energy converts from KE to PE and back again (Fig 9 pg 110)to PE and back again (Fig 9 pg 110) if the energy of the swing decreases, if the energy of the swing decreases,

then the energy of some other obj then the energy of some other obj must increase by an equal amount.must increase by an equal amount.

Friction converts some of the Friction converts some of the mechanical energy into thermal mechanical energy into thermal energyenergy

Fission vs FusionFission vs Fusion

Converting mass into energy, the total Converting mass into energy, the total amount of mass and energy are amount of mass and energy are conserved.conserved.

Nuclear Fusion-when 2 nuclei are fused Nuclear Fusion-when 2 nuclei are fused together- occurs in stars and the suntogether- occurs in stars and the sun

Nuclear Fission- two nuclei are broken Nuclear Fission- two nuclei are broken apart (nuclear power plants use this)apart (nuclear power plants use this)

Energy in your bodyEnergy in your body

CPE-from food that is stored in your CPE-from food that is stored in your body is used to keep you alive.body is used to keep you alive.

A food calorie is a measure of how A food calorie is a measure of how much energy you get from various much energy you get from various foods. One Calorie=4,180J.foods. One Calorie=4,180J.