Physics P1

• What is a system?

  an object or group of objects.
• what happens when something changes in a system

  Energy is transferred between its stores or to the surroundings
• what is a closed system

  no energy can escape to or enter from the surroundings.
• does the total energy in a closed system change

  no it never changes
• kinetic energy is


  the energy an object has because it is moving
• gravitational potential energy is


  energy an object has because of its height above the ground
• elastic potential energy is

  energy an elastic object has when it is stretched or compressed
• What is thermal energy?

  Energy an object has because of its temperature
• What does thermal energy consist of?


  The total kinetic and potential energy of the particles in the object
• chemical energy is


  energy that can be transferred by chemical reactions
• nuclear energy is


  energy stored in the nucleus of an atom
• magnetic energy is


  energy a magnetic object has when it is near a magnet or in a magnetic field
• electrostatic energy is


  energy a charged object has when near another charged object
• energy transfers can be

  transferred to and from different stores
• heat transfers are


  Energy is transferred from one object to another object with a lower temperature.
• wave transfers are


  Waves (e.g., light and sound) can transfer energy.
• electric transfers are


  An electric current transfers energy.
• force transfers are


  Energy is transferred when a force moves or changes the shape of an object.
• what is work done

  when an object is moved by a force
• work done equation


  force x distance
• gravitational potential equation


  mass x gravitational field strength x height
• kinetic energy equation


  1/2 x mass x velocity^2
• elastic potential energy equation


  1/2 x spring constant x extension^2
• power equation


  Work done / time
• Can energy be created or destroyed?

  No, it can be changed from one form to another
• can energy be entirely transferred usefully?

  no, some energy is always dissipated,
• what does dissipated mean

  when energy is transferred to less useful stores.
• where does all energy end up?

  the thermal energy store of the surroundings.
• lubrication is


  a way of reducing unwanted energy transfer due to friction.
• streamlining is


  a way of reducing energy wasted due to air resistance or drag in water.
• thermal insulating is used for?

  reducing energy wasted due to heat dissipated to the surroundings.
• Efficiency is


  a measure of how much energy is transferred usefully.
• Efficiency equation is


  Useful energy output / total energy input
• how to give efficiency as a percentage


  multiply the result from the calculation by 100 and add the % sign to the answer.