Physics - 3 energies

• Kinetic energy


  The energy stored in moving objects
• Calculating kinetic energy


  Kinetic energy (in Joules) = 0.5 x mass (in kg) x speed^2 (in m/s)
• A car runs on petrol (chemical energy)

  Some of the energy is converted to kinetic energy as the car moves
• Scientists often convert Joules to kilojoules by dividing by 1,000
• Elastic potential energy


  Energy stored in a stretched spring
• Stretching a spring


  1. Applying a force

  2. Doing work

  3. Storing energy
• Spring


  • Extension is directly proportional to the force applied
  • Has a limit of proportionality beyond which it will not return to original length
• Spring constant


  Value that depends on the specific spring
• Extension


  • 20 cm
• To use the formula, the extension must be in meters
• The spring constant in the example is 100 N/m
• Gravitational potential energy


  The energy stored in an object due to its position above the Earth's surface, due to the force of gravity acting on the object
• Changing chemical energy to gravitational potential energy


  Lifting an object off the ground and placing it on a shelf
• Changing gravitational potential energy to other forms of energy


  Allowing an object to fall off a shelf back to the ground
• Gravitational field strength


  A measure of the force of gravity
• Gravitational potential energy


  The energy stored in an object due to its position above the Earth's surface, due to the force of gravity acting on the object
• Changing chemical energy to gravitational potential energy


  Lifting an object off the ground and placing it on a shelf
• Changing gravitational potential energy to other forms of energy


  Allowing an object to fall off a shelf back to the ground
• Gravitational field strength


  A measure of the force of gravity