Energy and Heat Mr. T Gainesville Middle
What is Energy? Energy is defined as the ability to do work. The metric unit for energy is the joules (J)
Forms of Energy Energy comes in two forms: A. Potential B. Kinetic
POTENTIAL ENERGY Energy that is stored based on Position (gravitational) or in Chemical bonds. P.E.= MGh
ROCKS ON A HILL HAVE ENERGY DUE TO POSITION. GRAVITY PULLS THEM DOWN
POTENTIAL ENERGY Chemical Bonds: It takes energy to create chemical bonds. This energy in the bond is considered potential energy.
KINETIC ENERGY Energy of motion.
KINETIC ENERGY An objects kinetic energy can be calculated with a formula: K=mv 2 2 M=Mass V= Velocity (speed)
KINETIC ENERGY Both mass and speed can change the amount of kinetic energy an object has. Example: two identical cars, one going 30 Km/hr and one going 60 Km/hr will not have the same amount of kinetic energy. Speed has more affect on kinetic energy than mass because speed is squared.
Potential to Kinetic to Potential… Energy in an object may consists of either potential or kinetic or a combination of both.
Types OF ENERGY Energy comes in many types. These types of energy can be changed (transformed or converted) in other types. Thermal (heat) Light (Electromagnetic) Mechanical Nuclear Chemical Electrical
MECHANICAL Energy of motion! Pistons in an engine, water falling, a camel turning a stone wheel to grind grain, and sound are all examples of mechanical energy.
SOUND WAVES Sound is created when objects vibrate. This energy then travels through objects.
Particles that vibrate give off waves of energy called sound.
CHEMICAL ENERGY Chemical energy is a form of potential energy. The forces that hold the bonds together are storing energy. When you break the bonds, energy is released.
LIGHT ENERGY Light energy (Part of the Electromagnetic spectrum) also involves the movement of energy in waves, BUT unlike sound, this energy does not cause other objects to vibrate. Light energy unlike sound energy can travel through a vacuum ( an area containing no matter).
ELECTRICAL ENERGY Electrical energy is created by moving electrons.
NUCLEAR ENERGY This form of energy is associated with changes in the nucleus of atoms. Remember the strong force that holds the nucleus together?
NUCLEAR ENERGY Energy is released from the nucleus of an atom in one of two ways: A: FUSION B. FISSION
NUCLEAR FUSION In nuclear fusion 2 or more nuclei join together. Here 2 isotopes of Hydrogen join to form a Helium atom and a stray neutron.
NUCLEAR FUSION Nuclear fusion in the sun produces unbelievable amounts of energy from small amounts of hydrogen atoms.
NUCLEAR FISSION Nuclear fission occurs when large atoms (nuclei) are split apart to form 2 smaller nuclei.
NUCLEAR FISSION
USES OF NUCLEAR ENERGY 1. Power 2. Weapons 3. Medicine
NUCLEAR POWER PROBLEMS Waste disposal Nuclear power produces radioactive waste that has to be disposed of. This waste remains radioactive for 1000’s of years and so there is no really totally safe place to put the waste.
THERMAL ENERGY (HEAT) Thermal energy is a form of kinetic energy because it involves the movement of the particles in a substance. 2 main ideas here: A. The faster the particles are moving the more energy they have. B. The more particles you have the more thermal energy there is.
THERMAL ENERGY As the particles get more energy they move faster and spread apart. This is why we have state of matter. As the motion increases so does the temperature.
THERMAL ENERGY Which cylinder has the greatest amount of thermal energy?
THERMAL ENERGY The red cylinder because it has the most particles (volume)
EINSTEIN Matter can be changed into energy. Einstein developed a mathematical formula to prove this.
EINSTEIN! E = m c 2 This equation says: E [energy] equals m [mass] times c 2 [c stands for the velocity or the speed of light. c 2 means c times c, or the speed of light raised to the second power -- or c-squared.]
LAW OF CONSERVATION OF ENERGY Energy is neither created nor destroyed but changed (transformed) into other forms.
THERMAL ENERGY (HEAT) Thermal energy is a form of kinetic energy because it involves the movement of the particles in a substance. 2 main ideas here: A. The faster the particles are moving the more energy they have. B. The more particles you have the more thermal energy there is.
MEASURING HEAT ENERGY What is temperature? Temperature is a measure of the average KINETIC energy of the particles in an object.
MEASURING TEMPERATURE We use a Thermometer to measure temperature. There are three different scales commonly used: 1. Fahrenheit 2. Celcius 3. Kelvin
HOW DO THERMOMETERS WORK? As something gains or loses energy, the atoms and molecules move faster, spreading apart or slower, moving closer together. Energy from the object enters or leaves the thermometer and causes the liquid in the thermometer to either expand( gains energy) or shrink( loses energy).
ABSOLUTE ZERO If you remove absolutely all the energy in a substance or atom, all motion stops. This point would be absolute zero.
MYSTERY! You have a form of thermometer in your house working right now! Do you know where it is and what it is doing?
THERMOSTAT! Thermostats are basically a thermometer that works on a coil. The metal coil expands or shrinks in response to temperature. When it is cold the shrinking coil trips a switch to turn on your heater.
PHASE CHANGES Matter changes physical state when we add or take away energy. SOLID LIQUID GAS PLASMA
CHANGES OF STATE When changes is energy causes matter to undergo a phase change Terms to know: Melting point, Boiling point, Freezing Point, Condensing, Evaporation, Sublimation, Deposition
WHATS IN A TERM? Boiling/Evaporation: Liquid to Gas Condensation: Gas to Liquid Freezing: Liquid to Solid Sublimation: Solid to Gas Deposition: Gas to Solid Melting: Solid to Liquid
HEAT TRANSFER Heat is transferred from one object to another or from one place to another in one of three ways. 1. CONVECTION 2. CONDUCTION 3. RADIATION
HOW DOES HEAT MOVE? Heat always moves from warm areas to cold areas.
CONVECTION Movement of heat through air or liquids. Warm air or liquid becomes less dense and rises while cooler air or liquid sinks.
CONDUCTION This is where one object transfers heat directly through contact with another object.
RADIATION Transfer of energy through matter or space as electromagnetic waves. Radiation can travel through a vacuum.
WHAT IS AN INSULATOR? Materials that do not conduct heat well are called insulators. Can you think of some common things that we use as insulators?