Conservation and Dissipation of Energy - Paper 1

Question 1

Explain the Law of Conservation of Energy

Answer 1

Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed.

Question 2

How can an energy transfer in a closed system change its total energy?

Answer 2

No energy transfer in a closed system will lead to a net change in its total energy.

Question 3

Describe energy dissipation

Answer 3

In all system changes energy is dissipated (or ‘wasted’) so that it is stored in less useful ways.

Question 4

How can unwanted energy transfers be reduced?

Answer 4

e.g. lubrication, thermal insulation, etc

Question 5

How does the thermal conductivity of a material affect the rate of energy transfer by conduction across it?

Answer 5

The higher the thermal conductivity of a material the higher the rate of energy transfer by conduction across the material.

Question 6

How is the rate of cooling of a building affected by the thickness of its walls?

Question 7

How is the rate of cooling of a building affected by the thermal conductivity of its walls?