Energy Stores & Transfers (OCR GCSE Physics A (Gateway Science Suite)): Revision Notes

1.1.1 Energy Stores & Transfers

Energy Stores

Energy is stored in different types of energy stores. The main types include:

• Kinetic Energy: Stored by an object that is moving.
• Magnetic Energy: Stored by two magnets that are either attracting or repelling each other.
• Thermal Energy: Stored in an object due to its heat.
• Chemical Energy: Stored in chemical bonds.
• Electrostatic Energy: Stored by two charges that are attracting or repelling each other.
• Elastic Potential Energy: Stored in an object that has been stretched or compressed.
• Gravitational Potential Energy: Stored by an object when it is lifted to a height.
• Nuclear Energy: Stored inside the nuclei of atoms.

Keywords

Keyword	Definition
Wasted energy	Energy is transferred into a form that is not the desired outcome
Conservation of energy	Energy cannot be created or destroyed, only transferred
Specific heat capacity (c)	The amount of energy required to raise the temperature of 1 kg of a substance by 1°C
Renewable energy	Sources of energy that never run out (solar power, wind power, hydroelectric power, tidal power, wave power, geothermal energy, biofuels)
Non-renewable energy	Energy sources that cannot be replenished once depleted (oil, coal, gas, nuclear power)

Energy Transfers

Reducing Energy Waste

• Lubrication:
  • Example: Oil in a motor reduces friction, meaning less energy is lost as heat.
• Thermal Insulation:
  • Example: Double glazing reduces the amount of thermal energy lost from a building.

Thermal Conductivity

• Higher thermal conductivity in a material allows heat to travel through it more easily, increasing the rate of energy transfer by conduction.
• Thermal Conductivity in Buildings:
  • The rate of cooling is slower if the walls are thick and have low thermal conductivity.
  • If walls are made of thin metal sheets, heat would be lost very quickly.

Efficiency

Efficiency=Total energy inputUseful energy output​=Total power inputUseful power output​

• Increasing Efficiency:
  • Reduce waste output: Methods like lubrication and thermal insulation help.
  • Recycle waste output: For example, thermal waste can be captured and reused as input energy.

Increasing Efficiency of Energy Transfer

• The lower the thermal conductivity of a material, the less energy is lost as heat.
• Walls: Insulating material in the wall cavity helps reduce thermal energy loss.
• Windows: Double-glazed windows minimise heat loss.
• Roof: Loft insulation helps retain heat inside the house.

Diagram