Introduction to Energy: Work, Kinetic Energy, and Potential Energy

1. 12/10 • What is energy? • What is work? • Explain how the two are related? • What is kinetic energy? • Give an example of kinetic energy.

2. B A C E D 1/6 • What is kinetic energy? Potential Energy? • What is mechanical energy? • Explain what is happening at each letter. • If the mechanical energy at C was 100J and the potential was 50J, what is the kinetic energy? • If the kinetic energy at D is 100J, what is the potential energy?

3. What is Energy? Energy - the ability to do work Work - occurs when a force causes an object to move in the direction of that force • When one object does work on another, energy is transferred. Therefore work is a transfer of energy

4. Energy Transfer 1. 2. 3. Tennis player can do work on her racket because she has energy. Energy transfers from person to racket. The racket gains the ability to do work on the ball. Racket hits ball, energy is transferred from racket to ball.

5. Energy in Motion Kinetic Energy - energy of motion, dependent on the mass and velocity (speed) of an object Energy depends on mass and velocity (speed)

6. 25 m/s 25 m/s 20 m/s Kinetic Energy Kinetic Energy mv2 2 = • Which vehicle has the most kinetic energy? • Why? • Which vehicle has the least kinetic energy? • Why? The big truck Greatest mass and high velocity Smaller car on left Lower mass and least velocity

7. The faster something is moving the more kinetic energy it has The more massive something is the more kinetic energy it has

8. Potential Energy Potential Energy - stored energy, due to position or shape; “energy of position” • Potential energy depends on the weight of the object and its height above the earth’s surface. • It is effected by gravity! 1) The energy it takes to pull back the bow is stored until the bow is released! 2) The energy is then transferred to the arrow.

9. Mechanical energy sums it all up! Mechanical Energy - the total energy of motion and position of an object (sum of the KE and PE) MECHANICAL ENERGY = Potential energy + Kinetic energy ME = PE + KE • As potential energy increases, kinetic energy decreases increases • As potential energy decreases, kinetic energy • As potential or kinetic energy changes, mechanical energy stays the same

10. Most roller coasters use potential energy stored by gravity on the first hill to provide the energy for the rest of the ride. As the roller coaster goes down the hill, potential energy is transformed into kinetic energy. At the bottom of the first hill, the roller coaster has the highest speed. This is where the roller coaster has the most kinetic energy and very little potential energy. An electric motor pulls a roller coaster car up the first hill by a chain. The roller coaster car gains speed as it falls down to the bottom the first hill. The roller coaster car then goes up a second smaller hill. Describe the energy transformations: The __________________ energy in the wires are transformed into mechanical energy by the motor. The mechanical energy of the motor is transformed into _____________ energy of the roller coaster at the top of the first hill. As the roller coaster falls, its ______________ energy is transformed into mostly ___________ energy at the bottom of the hill. As the roller coaster climbs to the top of the second, smaller hill, some of its ___________ energy is transformed into _______________ energy.

14. Online Gizmos Potential Energy Gizmo: http://explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=399 Pendulum Gizmo: http://explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=390

15. Roller Coaster Physics!

16. Roller Coaster Physics! 1) When is the coaster’s potential energy at its highest? 2) When is the coaster’s kinetic energy at its highest? 3) What condition must be met for the coaster to continue moving after the first hill? 4) In theory, the mechanical energy shouldn’t change at all, but in reality it decreases a bit. Why?

20. Paragraph • Pick an activity • Explain how work, energy, kinetic and potential are involved in the activity. • Explain the final statement “when work is done the same amount of energy is involved.” • Or you can draw a diagram and explain the diagram in terms of the above information.

21. Identify the following as having either potential or kinetic energy: Coal ___________________________ Mrs. Pustay rolling down a hill ___________________________ Holding a ball before throwing it ___________________________ The ball flying through the air ___________________________ burning coal ____________________________ a lit match ___________________________ Mr. Saska swinging on a swing ___________________________ Humpty dumpty sat on a wall ___________________________ Humpty dumpty had a great fall ___________________________ A car traveling at 100 mph along a flat road ___________________________ A rubber band that has been stretched. ___________________________ A piano lifted to a second story window. ___________________________

22. Energy Box- Here is a list of all the different forms of energy Thermal Sound chemical Light Electrical Nuclear Using the letters next to the forms of energy in the “Energy Box” above write down any of the forms of energy you think are involved with each statement. (You can use more than one energy) 1. __________ A garden of vegetables growing. 5. ________ A passenger train 2. __________ A DVD player 6. ________ Eating a cheese steak hoagie 3. __________ A person playing the piano 7. ________ Jogging 4. __________ The sun 8. ________ A Power Plant Use the “Energy box” above to match each definition. • ____ Energy of moving electrons. • ____ Energy produced by the vibrations of electrically charged particles. • ____ Energy associated with the changes in the nucleus of an atom. • ____ Energy of a compound that changes as its atoms form new compounds. • ____ Energy of an object’s particles vibrating. • ____ Total energy of the particles that make up an object. Answer: • When a nucleus of an atom is split (more, less) energy is produced than when you eat a banana. • Microwaves, radio signals, DVD players, and lamps are all associated with what type of energy. • What happens to the particles in a guitar string when you pluck it? • Why do you think the sun is the most important energy resource? Minimum of 2 sentences! 5. Give an example of one type of energy converting into another type. Minimum of 2 sentences

23. Read your poem, break it down and discuss/write how these are related to different parts of the poem: Energy Work Kinetic energy Potential energy Mechanical energy Be ready to present!