Topic 3 : Conservation of energy

Question 1

Closed system

Answer 1

Closed System: A system that experiences no net change in its total energy when energy transfers occur within it.

Question 2

Conservation of energy

Answer 2

Conservation of Energy: The law that energy can be transferred, stored or dissipated but never created or destroyed.

Question 3

Efficiency

Answer 3

Efficiency: The ratio of useful output energy transfer to total energy input. It can never exceed 1 (or 100%), due to the conservation of energy.

Question 4

Fossil fuels

Answer 4

Fossil Fuels: Coal, oil and gas.

Question 5

Gpe

Answer 5

Gravitational Potential Energy: The store of energy that all raised matter has. It is directly proportional to the mass of the object, the distance that it is raised, and the gravitational field strength at that point.

Question 6

Kinetic energy

Answer 6

Kinetic Energy: The store of energy that all moving matter has. It is directly proportional to the object’s mass and to the square of its velocity.

Question 7

Lubrication

Answer 7

Lubrication: The application of a lubricant (such as oil) to reduce the friction that acts between surfaces. This may improve the efficiency of a system.

Question 8

Non rewnewabsle

Answer 8

Non-Renewable Energy Resource: An energy resource that cannot be replenished whilst it is being used. It is a finite resource.

Question 9

Rewnewable

Answer 9

Renewable Energy Resource: An energy resource that can be replenished whilst it is being used.

Question 10

Thermal insulation

Answer 10

Thermal Insulation: The application of a material that reduces the amount of heat that is transferred from the system in question, to its surroundings.

Question 11

Useful energy transfer

Answer 11

Useful Energy Transfer: The transfer of energy by a system, to directly serve the purpose of the system.
Waste Energy Transfer:

Question 12

Waste energy transfer

Answer 12

Waste Energy Transfer: The transfer of energy by a system to a form that doesn’t directly serve the purpose of the system.

Question 13

Waste energy

Answer 13

Waste Energy
- Forms: Light, sound, (most commonly) heat
- To reduce waste:
Lubricate systems, so less friction and less heat created
Thermal insulation, so less heat is lost to surroundings
- Buildings
• Thicker walls mean greater thermal insulation, so less heat is lost
• Air cavities between walls causes lots of heat loss by convection - cavity wall insulation fills in this gap and prevents air flow

Question 14

Energy sources

Answer 14

• Fossil Fuels
  Nuclear Fuel
  Bio-Fuel
• Wind
  Hydro-electricity
  Tidal
• Solar

Answer 15

Efficiency can be increased by:
Reducing waste output (via lubrication/thermal insulation or other methods)
Recycling waste output and using it as input (absorbing heat energy dissipated and used to as input heat energy)
Suitable methods depend on each situation