Chapter 4

 Ability to cause change  Lots of forms  Light/radiant  Sound  Electrical  Chemical  Heat/thermal  Nuclear  Mechanical

 Energy of motion  Depends on  Mass of object  Speed of object  E k = ½ mv 2  Unit: Joule (J)

 Stored energy due to position  Elastic  Stored in something that can be stretched or compressed  Chemical  Stored in chemical bonds

 Gravitational  Energy stored by object due to position above Earth’s surface  Depends on  Mass of object  Height of object  E g = mgh  Unit: Joule (J)

 Energy cannot be created or destroyed  But it can be TRANSFORMED  Light Bulb  Food  Radio

 Total energy remains constant

 E = mc 2

 Transfer of Energy  Force moves an object over a distance  Movement must occur in direction of force

 When work is done, energy is transferred  Doing work on object increases object’s energy  W = Fd  Unit: Joule (J)

 Rate of energy transfer  Rate at which work is being done  Power = Work/time  Unit: Watt (W)  1 HP = 746 W