energy

• applying a force to change length of a spring is classed as work
• kinetic energy is energy stored in moving objects
• kinetic energy = 0.5 x mass x speed^2
• energy stored in a stretched spring is elastic potential energy
• elastic potential energy = 0.5 x spring constant x extention^2
• gpe is the energy stored in an object raised in a gravitational field
• GPE = mass x field strength x height
• when a system changes the way energy is stored also changes
• elastic potential energy = 1/2 x spring constant x extension squared
• gravitational potential energy = mass x gravitational field strength x height
• an open system is one where things can enter in or out