The Nature of Energy Section 4.1

Energy Every change that occurs involves. Every change that occurs involves. Moving objects have energy Moving objects have energy You can tell an object has energy when it: You can tell an object has energy when it: Changes its environment Changes its environment Changes itself Changes itself Energy Energy Electrical – moving electrons Electrical – moving electrons Chemical – from bonds Chemical – from bonds Thermal- heat Thermal- heat

Energy Energy exists in many different forms Energy exists in many different forms It may look different, but it’s still energy. It may look different, but it’s still energy. Examples: fire, movement, gasoline in a bucket Examples: fire, movement, gasoline in a bucket Kinetic energy- energy in the form of motion Kinetic energy- energy in the form of motion Depends on mass and velocity of an object Depends on mass and velocity of an object Increase in either mass or velocity = increase in energy Increase in either mass or velocity = increase in energy KE =1/2 mv 2 KE =1/2 mv 2 Units = kg*m/s Units = kg*m/s

Types of Energy KE = ½ mv 2 Velocity changes will impact KE more because velocity is squared. KE = ½ mv 2 Velocity changes will impact KE more because velocity is squared. Potential Energy – energy of position Potential Energy – energy of position Energy in stationary objects and bonds Energy in stationary objects and bonds Elastic Potential Energy – Energy of compression or stretching Elastic Potential Energy – Energy of compression or stretching Chemical Potential Energy – Energy stored in bonds Chemical Potential Energy – Energy stored in bonds Gasoline, food, hand warmers Gasoline, food, hand warmers

Types of Energy Gravitational Potential Energy- Energy stored due to position above the surface of Earth Gravitational Potential Energy- Energy stored due to position above the surface of Earth Depends on mass of object, height of object above ground, and acceleration due to gravity Depends on mass of object, height of object above ground, and acceleration due to gravity GPE = m x h x g g = acceleration due to gravity GPE = m x h x g g = acceleration due to gravity All energy – measured in units of Joules All energy – measured in units of Joules 1 J = 1 kgm 2 / s 2 1 J = 1 kgm 2 / s 2 Energy can be converted: Energy can be converted: As an object falls, GPE decreases and KE increases As an object falls, GPE decreases and KE increases