Lesson I “Energy & Its Forms” Matter & Energy

S.W.B.A.T. Relate energy to work Relate energy to work Discuss kinetic and gravitational energy and the factors that affect both Discuss kinetic and gravitational energy and the factors that affect both Describe the basic forms of energy Describe the basic forms of energy

Energy & Work Energy is the ability to do work Energy is the ability to do work Work is done and energy is transferred by a force moving an object through a distance Work is done and energy is transferred by a force moving an object through a distance

Energy & Work Work is the difference in energy between start and finish Work is the difference in energy between start and finish Both work & energy are measured in the SI unit of joules Both work & energy are measured in the SI unit of joules

Energy & Work Example: energy for walking comes from your muscles - which is powered by the food you eat Example: energy for walking comes from your muscles - which is powered by the food you eat Food is converted into energy by chemical means Food is converted into energy by chemical means

Energy & Work Energy that created the food came from the Sun - plants and/or animals that ate the plants Energy that created the food came from the Sun - plants and/or animals that ate the plants There are many forms of energy There are many forms of energy Video (6:07) “Bill Nye on Energy Part 2Video (6:07) “Bill Nye on Energy Part 2” Video (6:07) “Bill Nye on Energy Part 2

Kinetic Energy Kinetic energy (KE) is the energy of motion Kinetic energy (KE) is the energy of motion The KE of any object depends on its mass & speed The KE of any object depends on its mass & speed

Kinetic Energy KE = 1/2mv 2 KE = 1/2mv 2 Double the mass (m) and you get 2 times the kinetic energy Double the mass (m) and you get 2 times the kinetic energy Doubling the speed (v 2 ) quadruples the energy! Doubling the speed (v 2 ) quadruples the energy!

Potential Energy Potential energy (PE) is energy that is stored as a result of position or shape Potential energy (PE) is energy that is stored as a result of position or shape Example: a raised object like a book or a ball has stored PE Example: a raised object like a book or a ball has stored PE

Examples of Potential & Kinetic Energy

Potential Energy Gravitational Potential Energy (GPE) – energy that increases with height Gravitational Potential Energy (GPE) – energy that increases with height GPE depends on mass, height & acceleration due to gravity GPE depends on mass, height & acceleration due to gravity

Potential Energy Ex. a diver on a diving board has stored GPE Ex. a diver on a diving board has stored GPE Potential Energy equals mass x gravity x height Potential Energy equals mass x gravity x height Or PE = mgh Or PE = mgh

Potential Energy Elastic Potential Energy – when an object is stretched or compressed Elastic Potential Energy – when an object is stretched or compressed Ex. stretching a rubber band or bouncing a basketball filled with compressed air Ex. stretching a rubber band or bouncing a basketball filled with compressed air

Forms of Energy Mechanical energy – equals the sum of both kinetic & potential energy Mechanical energy – equals the sum of both kinetic & potential energy Or ME = KE + PE Or ME = KE + PE Examples include speeding trains; bicycling & sprinting athletes Examples include speeding trains; bicycling & sprinting athletes

Forms of Energy Thermal energy is equal to the total PE & KE at the atomic level Thermal energy is equal to the total PE & KE at the atomic level Every object emits some thermal energy (or heat) due to particles in random motion Every object emits some thermal energy (or heat) due to particles in random motion

Forms of Energy Chemical energy – stored energy in chemical bonds Chemical energy – stored energy in chemical bonds When chemical bonds are broken stored energy is released When chemical bonds are broken stored energy is released Examples include using gasoline in a car engine; consuming food & burning wood Examples include using gasoline in a car engine; consuming food & burning wood

Forms of Energy Electrical energy – energy associated with moving electrons or electric charges Electrical energy – energy associated with moving electrons or electric charges Examples include batteries (also stored chemical energy) and lightning Examples include batteries (also stored chemical energy) and lightning

Forms of Energy Electromagnetic energy – include light waves that travel though space Electromagnetic energy – include light waves that travel though space Examples include radio waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays Examples include radio waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays

Forms of Energy Nuclear energy – energy stored in an atom’s nucleus Nuclear energy – energy stored in an atom’s nucleus Fission splits the atom’s nucleus to generate tremendous energy Fission splits the atom’s nucleus to generate tremendous energy Fusion combines the nuclei of atoms Fusion combines the nuclei of atoms

Examples of Potential & Kinetic Energy Video (2:02) “Bill Nye on EnergyVideo (2:02) “Bill Nye on Energy” Video (2:02) “Bill Nye on Energy

Class Activity A 70 kg person walks up a hill that is 300 m in height A 70 kg person walks up a hill that is 300 m in height What is the person’s gravitational potential energy (GPE) at the top of the hill? What is the person’s gravitational potential energy (GPE) at the top of the hill?