Energy What is energy ENERGY is the ability

Energy

• What is energy? • ENERGY is the ability to cause change. • There are many different kinds of energy. • Everything around us has energy – YOU have a large amount of energy. • When change occurs, energy is transferred from one object to another. – Footsteps transfer energy from foot to ground to ears. – Warmth is felt when the sunlight transfers energy to a table or chair. – Where do you see energy?

Energy of Motion • KINETIC ENERGY is the energy an object has due to its motion. • KE = ½ x mass x (velocity)2 • The faster something is moving, the more kinetic energy it has. • The heavier a moving object is, the more kinetic energy it has.

Which one has greater KE? • Two vehicles, a semi and a VW beetle, traveling at 60 mph each • A snowball thrown or a cannonball fired • A bullet fired or a bowling ball rolled down a lane

Energy of Position • POTENTIAL ENERGY is the energy an object has based on its position. • PE = mass * gravity * height • Objects very high up have lots of potential energy.

Which picture has greater PE? YOU R -O

Total Energy • The TOTAL ENERGY is the combination of kinetic and potential energy of a system. • TE = KE + PE • The LAW OF CONSERVATION OF ENERGY states that energy can neither be created nor destroyed – it only changes forms.

Practice! • https: //www. youtube. com/watch? v=iz. Ve. Vfcf. S ws • Where is Higgins’s potential energy the greatest? • What happens to his kinetic energy as he rolls down the hill?

• Draw a picture of what Higgins’s path might have looked like. • What happens to Higgins’s potential energy as he rolls down the hill? • What happens to his total energy? • At the very end, where does all the energy from his motion go?

Phet demonstration • We are going to look at an online demonstration, and decide where potential and kinetic energy are the highest. – What is happening as the skateboarder goes up/down the hill? – What is happening to their total energy? – What happens if we change the ramp?

• INTRO – Using the U-shaped track, examine the motion of the skater. • • Is energy conserved? Where is KE, PE the highest? – Click on “Bar graph” Notice where the skater’s speed is the highest – Click on “Speed” – How does this relate to KE? PE? Notice where the skater’s height is the highest – Click on “Grid” – How does this relate to KE? PE?

• Friction –Using the U-shaped track, examine the motion of the skater. • Is energy conserved? • If you leave the skater alone, what eventually happens? –Click on “Speed” • Where does this energy go? –Click on “Bar graph”

Activity! – Human Continuum • During this activity, you will be asked to stand in an area of the room that represents your answer to a question. • You may be asked to defend your answer – be ready to give your reasoning!

A skater starts at the top of a ramp. Is his energy: Potential? Kinetic? Thermal?

A skater is at the bottom of the ramp, quickly moving up to the other side. His energy is: • Kinetic, potential, or a mix?

• Where is this skater on the ramp, given his energy? Top (moving up) Bottom Middle Top (moving down)

Same question – where is this skater? Top Middle Bottom

Top Middle Bottom

• In which position does the skater have the most…? • Kinetic energy • Potential energy • Total energy E A C D B

• At the highest point kinetic energy is zero / maximum while the potential energy is zero / maximum. • At the lowest point kinetic energy is zero / maximum while potential energy is zero / maximum. • Mass affects / does not affect the amount of energy.

• As an object falls in gravity, kinetic energy increases / decreases / remains the same. • As an object falls in gravity, potential energy increases / decreases / remains the same. • As an object falls in gravity, total energy increases / decreases / remains the same.

• An object travelling faster and faster has a kinetic energy that increases / decreases / remains the same. • An object travelling faster and faster has a potential energy that increases / decreases / remains the same. • As an object speeds up, the total energy increases / decreases / remains the same. • As an object slows down, the total energy increases / decreases / remains the same.