Energy

Nature of Energy  Energy is all around you.  You hear energy as sound  You see energy as light

Nature of Energy  You can feel energy in wind

Nature of Energy  Living organisms need energy for growth and movement

Nature of Energy  You use energy when  You hit a tennis ball  Compress a spring  Lift a grocery bag

Energy is …  The ability to do work!  The energy released by a supernova is capable of destroying a nearby solar system in just a few hours. A supernova is one of the greatest concentrations of energy in the universe.

Forms of Energy  Energy appears in many forms. There are five main forms of energy.  Mechanical  Heat  Chemical  Electromagnetic  Nuclear

Mechanical Energy  Energy of motion  Examples include  Water in a waterfall  Wind  Moving vehicles  Sound

Heat Energy  The internal motion of atoms.  The faster the molecules move, the more heat energy is produced.  Examples include  Friction  Changes in the state of matter

Chemical Energy  Energy that exists in the bonds that hold atoms together.  When bonds are broken chemical energy is released.  Examples include  Digesting food … bonds are broken to release energy for your body to store and use.

Chemical Energy (cont)  More examples  Sports … your body uses energy stored in your muscles obtained from food.  Fire – a chemical change

Electromagnetic Energy  Moving electric charges.  Examples include  Power lines carry electricity  Electric motors are driven by electromagnetic energy

Electromagnetic Spectrum  Light is just one of the forms of energy that fall in the electromagnetic spectrum.

Nuclear Energy  When the nucleus of an atom splits, nuclear energy is released.  Nuclear energy is the most concentrated form of energy.

Nuclear Energy (cont.)  Nuclear Fission - is a nuclear reaction in which the nucleus of an atom splits into smaller parts; which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments nuclear reactionnucleusenergyelectromagnetic radiationkinetic energynuclear reactionnucleusenergyelectromagnetic radiationkinetic energy

Nuclear Energy (cont.)  Nuclear Fusion - is the process in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy. atomic nucleienergyatomic nucleienergy

Questions  What is energy?  Can energy be transferred from one object to another?  What are the different forms of energy?

States of Energy  There are two states of energy  Potential  Kinetic

Potential Energy  Stored energy – energy of position.  Not always mechanical energy – can be other forms.  Gravitational Potential energy depends on height and weight.  GPE = Weight x Height  Units –Newton/meter

Kinetic Energy  The energy of motion.  The faster the object moves – the more kinetic energy.  Kinetic energy depends on both mass and velocity.  KE = ½ (mass x velocity 2 )  Kg m 2 /s 2  Units - Joules

Wasted Energy Whenever an energy transfer occurs some energy is ALWAYS WASTED. Where does this energy go to? It SPREADS OUT and is LOST to the SURROUNDINGS. It is very hard to REUSE. This is why we should be mindful not to waste energy needlessly. What is the wasted energy for an electrical lamp? A lamp is designed to change electrical energy into light energy. Some energy is wasted in the form of HEAT though. In fact, ALL ELECTRICAL devices WASTE ENERGY in the form of HEAT. If you could hear the lamp buzzing then it would be wasting energy in the form of SOUND.

Exercise 8: Wasted Energy 1.What happens to wasted energy? 2.In which two forms is energy usually wasted? 3.In what form do all electrical devices waste energy? 4.If you can hear a device that is not supposed to make a noise, in what form is energy being wasted? 5.In what forms does a hairdryer waste energy? 6.In what form does a coal fire waste energy? It spreads out into the surroundings and is harder to reuse. Heat and sound. Heat. Sound. Heat and sound. Light energy.

Energy Conversions  The most common energy conversion involves the changing of potential energy into kinetic energy or vice-versa.  Examples include  Ball thrown in the air  Roller coaster

More Conversions  All forms of energy can be converted to other forms.  Law of Conservation of Energy – Energy cannot be created or destroyed.  Einstein said – If matter is destroyed, energy is created; if energy is destroyed, matter is created. The total amount of mass and energy is conserved.