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Exploring Energy and Conservation Through Forms and Transformations

Understand the different forms of energy, including kinetic and potential, and how energy transforms while conserving its total amount. Learn about the laws of conservation of energy and the basics of temperature, thermal energy, heat, and specific heat. Dive into practical examples and applications of energy concepts.

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Exploring Energy and Conservation Through Forms and Transformations

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  1. Chapter 4 Energy

  2. What is energy? • Def: ability to cause change • Every change involves energy

  3. Different Forms • Electrical • Chemical – stored in food, involved in reactions • Radiant – gives off • Thermal – heat • Same thing just different forms

  4. Kinetic Energy • Def: energy of a moving object • Depends on mass and speed • Kinetic energy (Joules) = 1mass (kg) x [speed (m/s)]2 2 • KE = 1 mv2 2 • SI unit for energy is joule (J)

  5. Practice! • What is the kinetic energy of a .15 kg baseball moving at 40 m/s. • A car moving at a speed of 20 m/s has a kinetic energy of 300,000 J. What is the car’s mass?

  6. Potential Energy • Even motionless objects have energy • Stored in the object, has potential to change • Def: stored energy

  7. Elastic Potential Energy • Def: stored energy by something that can stretch or compress • Stretched rubber band – elastic potential energy  kinetic energy

  8. Chemical Potential Energy • Def: energy stored in chemical bonds • Food, gasoline, etc.

  9. Gravitational Potential Energy • Def: stored energy by objects due to position above earth (able to fall)

  10. Practice! • Find the height of a .15 kg baseball that has a GPE of 73.5 J. • Find the GPE of a .3 kg coffee mug on a 1-m high counter. • What could you do to change GPE? • Change height or mass

  11. Section 2 Conservation of Energy

  12. Changing Forms of Energy • Changing electrical energy – electricity – light and heat energy • Energy is constantly changing forms

  13. Transforming Chemical Energy • Cars – MANY energy transformations • Spark plug – gasoline – engine - wheels

  14. Transforming Chemical Energy • Green plants – take in sunlight and transform to chemical energy in plants

  15. Mechanical Energy • Def: total amount of potential and kinetic energy Mechanical Energy = Potential + Kinetic

  16. Falling Objects • As potential  kinetic mechanical energy stays same • Potential lost = kinetic gained

  17. Projectile Motion • Mechanical energy remains constant • Still see transformations of energy

  18. Swinging • Best part is falling from highest point • High GPE = Low KE • Describe transition…

  19. Law of Conservation of Energy • Def: energy can not be created or destroyed • Energy just changes form • All energy in the universe does not change • Energy in = Energy out

  20. Is energy always conserved? • Swinging – you eventually will stop – where does all the energy go? • Friction – air resistance = thermal energy

  21. Human Body – Energy Relations • What forms of energy are in your body? • Conservation of energy still true • Food, fat = potential energy • Activity = kinetic energy • Calorie 1C = 4,184 J

  22. Chapter 6 Section 1 Temperature and Heat

  23. Matter in Motion • Matter is made of tiny particles in constant motion  have kinetic energy • Faster = more kinetic energy

  24. Temperature • Def: measure of average kinetic energy of particles • High Temp. = High Energy • Low Temp. = Low Energy • Unit  Kelvin

  25. Thermal Energy • Collisions between air and butter particles increase energy of butter = higher temperature • Def: sum of kinetic and potential energy of particles in object

  26. Thermal Energy • As temp increases = thermal energy increases • If object has MORE MASS and at the same temp. has HIGHER thermal energy

  27. Heat • Is your seat toasty? • Def: thermal energy that flows from something at a higher temp to a lower temp • Unit: Joule

  28. Beachin’ it up! • How can there be extreme differences in temperature from air, sand and water? • Sun rays are the same why different temp? • Sand heats up 6 times faster than water

  29. Specific Heat • Specific Heat: heat needed to raise 1kg of material by 1C

  30. Water as a Coolant • It’s high specific heat – absorb a lot of heat without changing temp much • Strong bonds have to be broken before particles move really fast

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