1. Energy Chapter 15

2. Energy Energy = the ability to do work. Work = a transfer of energy. When work is done on an object, energy is transferred to that object.

3. Energy Measured in joules (J) 1 J = 1 Newton-meter (the work done when an object is moved 1 meter by a 1 Newton force) 1 N 1 METER

4. Carrying your backpack upstairs.. Lift backpack against gravity…WORK! Requires ENERGY! – From muscles – From food – From plants – From sun

5. Types of Energy Two Main Types – Kinetic Energy – Potential Energy

6. Kinetic Energy

7. Kinetic Energy Problem A 70.0 kg man is walking at a speed of 2.0 m/s. What is his kinetic energy?

8. Potential Energy Energy that is stored as a result of position or shape. – Guitar: Energy is stored in stretched string. Released, string vibrates stored energy is converted into kinetic energy

9. Potential Energy Energy that is stored as a result of position or shape. – Holding book in the air…potential energy – Let go…potential energy is converted into kinetic energy

10. Types of Potential Energy Gravitational Potential Energy Elastic Potential Energy

11. Gravitational Potential Energy

12. A diver on 10 meter diving platform has a mass of 50 kg. What is the diver’s gravitational potential energy? = 4900 J

13. Elastic Potential Energy The potential energy of an object that is stretched or compressed. – Rubber band is stretched – Let go…potential energy is converted to kinetic energy You did WORK

14. Compressed: basketball

15. Forms of Energy Mechanical Thermal Chemical Electrical Electromagnetic Nuclear

16. Mechanical Energy Mechanical energy = the energy associated with the motion and position of objects. The sum of an object’s potential energy and kinetic energy. Ex. Train, runner, bouncing balls

17. Thermal Energy The total potential and kinetic energy related to the motion of all the microscopic particles in an object. ATOMS! When an object’s atoms move faster, thermal energy increases, object becomes warmer.

18. Chemical Energy Chemical energy = the energy stored in chemical bonds When bonds are broken, the energy is released. The released energy can do work. Ex. Burning wood, gasoline in car

19. Electrical Energy Electrical energy = the energy associated with electric charges. Electric charges can exert forces that do work. Ex. Batteries convert chemical energy to electrical energy Ex. lightning

20. Electromagnetic Energy Electromagnetic energy = a form of energy that travels through space in the form of waves. Ex. Visible light, x-rays

21. Nuclear Energy Nuclear energy = the energy stored in atomic nuclei Fission = releases energy by splitting nuclei apart Fusion = nuclei combine to form a larger nucleus SUN

22. What is Energy? SciShow