Physics Energy (1)

• What are the eight energy stores?

  Chemical, thermal, kinetic, gravitational potential, elastic potential, electrostatic, magnetic, nuclear.
• How can energy be transferred?

  • By doing work (etc friction)
  • Falling objects (gravitation potential energy/kinetic energy)
  • Movement (kinetic energy)
  • Lifting an object (gravitational potential energy)
  • Stretching (elastic potential energy)
• The measure of how much energy a substance can store is called its specific heat capacity.
• What is specific heat capacity?

  Specific heat capacity is the amount of energy needed to raise the temperature of 1kg of a substance by 1 degrees.
• How do you investigate specific heat capacities?

  1. Grab a block of material with two holes in it (for the heater and thermometer)
  2. Measure the mass of the block, then wrap it in an insulating layer.
  3. Measure the initial temperature of the block and set a 10 v potential difference. Turn on the power supply and start stopwatch
  4. As the block heats up, use the thermometer to measure its temperature every minute.
  5. When you’ve collected 10 readings, turn off power supplies and calculate the specific heat capacity
• What is the conservation of energy principle?

  Energy can be transferred usefuly, stored or dissipated, but can never be created or destroyed.
• What is power?

  The rate of energy transfer or rate of doing work
• What is power measured in

  Watts, W
• What is energy transferred measured in?

  Joules, J
• What is conduction?

  Conduction is the process where vibrating particles transfer energy to neighbouring particles.
• The particles in the part of the object being heated vibrate more and collide with each other. These collisions cause energy to be transferred between particles’ kinetic energy stores. This is conduction.
• Conduction occurs mainly in solids
• What is convection

  Convection is where energetic particles move away from hotter to cooler regions
• Convection occurs only in liquids and gases as they can move.
• How do radiators create convection currents?

  1. Energy is transferred from the radiator to the nearby particles by conductions
  2. The air by the radiator becomes warmer and less dense
  3. The warm air rises and is replaced by the cooler air. The cooler air is then heated by the radiator
  4. At the same time, the heated air transfers energy to the surroundings, cooling down and becomes denser, sinking.
  5. The cycle repeats, causing a flow of air to circulate around the room (convection current)
• How does lubricant reduce unwanted energy transfers?

  Reduces friction
• What are some ways to reduce loss of heat energy?

  Thick walls made of material with a low thermal conductivity

  Cavity walls, Loft Insulation, double glazing, draught excluders.
• How could you investigate the effectiveness of different insulators?

  1. Boil water in a kettle and pour it into a sealable container. Measure the mass of water in the container.
  2. Use a thermometer to measure the initial temperature of the water
  3. Seal the container and leave it for five minutes. Measure this time using a stopwatch
  4. Remove the lid and measure the final temperature of the water
  5. Pour away the water and allow the container to cool to room temperature
  6. Repeat the experiment but wrap the container in a different material.
• What is efficiency?

  The less energy wasted, the more effiicient the thing is.