Energy

• What happens to energy in a system

  Energy is transferred between different stores
• What are the 8 types of energy stores

  1. Thermal
  2. Kinetic
  3. Gravitational potential
  4. Elastic potential
  5. Chemical
  6. Magnetic
  7. Electrostatic
  8. Nuclear
• Energy can be transferred in 4 different ways what are they

  • Mechanically
  • Electrically
  • By heating
  • By radiation
• Define what a system is in physics 


  A single object or a group of objects
• What happens when a system changes

  Energy is transferred into or away from the system
• What is a closed system

  Neither matter nor energy can enter or leave
• What is the net change in energy of a closed system

  Always zero
• How is energy transferred when boiling water in a kettle

  energy is transferred to the water by heating, into the waters thermal energy store
• What does work done mean in terms of energy

  It is energy transferred
• The initial force exerted by a person to throw a ball upwards does work. How?

  It causes an energy transfer from the chemical energy store of the persons arm to kinetic energy store of the ball and arm
• A ball dropped from a height is accelerated by gravity. The gravitational force does work. How?

  it causes the energy to be transferred from the balls gravitational potential energy store to its kinetic energy store
• What happens in a collision between a car and a stationary object

  It causes energy to be transferred from the cars kinetic energy store to other energy stores
• What typed of energy stores are involved in a car collision

  Kinetic, elastic and thermal
• How can is some energy transferred away during a collision

  By sound waves
• The friction between a cars break and it’s wheels does work as it slows down. How?

  It causes an energy transfer from the wheels kinetic energy stores to the thermal energy store of the surroundings
• The energy in the kinetic energy store depends on the objects something. What are they?

  Mass and speed
• What is the formula for kinetic energy

  Kinetic energy= 0.5*mass*speed
• What is required to lift an object in a gravitational field

  Work is required to lift the object
• What does the energy in a gravitational potential energy store depend on

  mass, height and gravitational field strength
• What is the formula for gravitational potential energy

  GPE= mass*gravitational field strength*height
• What happens to energy when an object falls without air resistance

  Energy is transferred from gpe to kinetic energy
• What effect does air resistance have on falling objects

  It causes energy to transfer to other stores
• What can stretching or squashing an object do

  Transfer energy to its elastic potential energy store
• What is the condition for energy in the elastic potential energy store to be calculated 


  The limit of proportionality must not be exceeded
• What is the formula for elastic potential energy

  Elastic potential energy=0.5*spring constant*extention
• What is the first topic summarized in the video?

  Energy
• What mnemonic helps remember types of energy?

  • Geeks Lunch Oldham
  • Gravitational potential energy
  • Electrical energy
  • Elastic potential energy
  • Kinetic energy
  • Sound energy
  • Light energy
  • Nuclear energy
  • Chemical energy
  • Thermal energy
• What does gravitational potential energy depend on?

  Mass, gravity, and height
• How is kinetic energy defined mathematically?

  $KE =$$\frac{1}{2}mv^2$
• What is the unit of kinetic energy?

  Joules
• What is the formula for elastic potential energy?

  $PE =$$\frac{1}{2}kx^2$
• What is the formula for gravitational potential energy?

  $PE =$$mgh$
• What is the gravitational field strength on Earth?

  9.8 N/kg
• What is the formula for change in thermal energy?

  $\Delta E =$$mc\Delta T$
• What is the unit for specific heat capacity?

  J/kg°C
• What is the formula for power?

  $P =$$\frac{E}{t}$
• What are the units for power?

  Watts
• What is the formula for efficiency?

  $\text{Efficiency} =$$\frac{\text{Useful energy out}}{\text{Total energy in}}$
• What is a renewable energy source?

  One that won't run out
• What is a disadvantage of solar power?

  It doesn't work at night