Energy Conversion and Conservation

1
Energy Conversion and Conservation
2
Review - Work

• Work is done when a force acts on an object in
  the direction the object moves.
• Work Force x Distance
• W F x D
• The joule (J) is the SI unit of work.

3
Review - Power

• Power is the rate of doing work.
• Power Work / Time
• P W/t
• The SI unit of power is the watt (W)

4
Review - Energy

• Work causes a change in the energy of a system.
• The two main types of energy are
• Kinetic
• potential

5
Review Kinetic Energy

• Kinetic energy depends on motion and is measured
  in joules (J).
• KE ½ mv2
• v velocity

6
Review Potential Energy

• Gravitational Potential Energy depends on height
  and is measured in joules (J).
• PE mgh
• h height
• g acceleration due to gravity 9.8m/s2

7
Energy Conversion

• Energy can be converted from one form to another.
• The process of changing energy from one form to
  another is energy conversion.
• EX Rubbing hands kinetic energy to thermal
  energy.

8
Conservation of Energy

• When energy changes from one form to another, the
  total energy remains unchanged.
• The law of conservation of energy states that
  energy cannot be created or destroyed.

9
Energy Conversions

• The gravitational potential energy of an object
  is converted to the kinetic energy of motion as
  the object falls.
• EX sky diving
• The kinetic energy of motion is converted to
  gravitational potential energy when an object is
  gaining height.
• EX pole vaulting

10
Energy Conversion in a Pendulum
11
Energy Conversion

• Your beginning energy must equal your ending
  energy. This allows us to say that
• (KE PE)beginning (KE PE)end
• Which means you can set kinetic energy equal to
  potential energy.