PAPER 1:Conservation and dissipation of energy

State the law of energy conservation

Energy can not be created or destroyed it can only be transferred into different forms

State any changes in the TOTAL ENERGY of a ball that is kicked assuming that no external force acts

The total energy of the system remains constant due to the conservation of energy

What is waste energy

The energy that is not used by the devide for its desired purpose

Describe the energy changes that occur in a filament light bulb

Electrical energy is transferred into light and heat energy

Light is a useful energy form , heat is waste energy

State TWO equations to calculate efficiency

=Useful output energy transfer/total input energy transfer

=useful power output/total power output

How can the efficiency of a system be increased

Reducing waste output (by lubrication, thermal insulation)

Recycling waste output (eg Recycling thermal waste energy as input energy)

State the consequences for energy transfer of a material with a high thermal conductivity

The rate if energy transfer through thr material is higher thsy for a material woth a lower thermal conductivity

Do double glazes windows have a higher or lower thermal conductivity than single glazed windows

Lower meaning less energy transfers through them

What key factors affect the rate of cooling of a building

The thickness of the walls

The thermal conductivity of the walls

State THREE methods of reducing heat loss in a building

Double glazing

Loft and wall insulation

Thicker walls

How can the efficiency of a mechanical machine with moving parts be improved

Lubricate any moving parts to reduce thr friction and therefore energy loss due to heating

How can the efficiency of a radiator be improved

Installing metal foil sheets behind the radiator to reflect the heat back into the room rather than it being absorbed into the walls

How can the efficiency of boiling water in a pan be reduced

By placing a lid on the pan to reduce heat loss from the top