Conservation & Dissipation

Question 1

Principle of conservation of energy

Answer 1

Energy can be transferred usefully, stored or dissipated but cannot be created or destroyed
During energy transfers, some energy is dissipated - stored in less useful ways
Reduce unwanted energy transfers: lubrication, insulation

Question 2

In what state of matter does conduction occur?

Answer 2

Mainly solids

Question 3

In what state of matter does convection occur?

Answer 3

Mainly liquids & gases

Question 4

What is conduction

Answer 4

Vibrating particles transfer energy to neighbouring particles

Question 5

Thermal conductivity

Answer 5

How quickly energy is transferred through a material by conduction

Question 6

Convection

Answer 6

Where particles with lots of thermal energy displace particles with less thermal energy. Leads to a convection current

Question 7

Reducing heat loss in a Building

Answer 7

Cavity wall insulation (low thermal conductivity), loft insulation (reduces convection currents), double glazing, draught excluders

Question 8

Efficiency

Answer 8

How well an object outputs useful energy, compared to how much energy is taken in

Question 9

Efficiency formulas

Answer 9

Efficiency = useful output energy transfer/total input energy transfer

Efficiency = useful power output/total power output

Question 10

Increasing efficiency

Answer 10

Lubricants reduce friction (usually liquids - flows easily)
Thermal insulation helps keeps warmth