conservation and dissipitation of energy

Question 1

state the law of energy conservation

Answer 1

energy cannot be created or destroyed.

Question 2

state any changes in the total energy of a ball that is kicked, assuming that no external forces act

Answer 2

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

Question 3

what is waste energy

Answer 3

the energy that is not used up by the device for its desired purpouse

Question 3

describe the energy changes that occur in a filament light bulb

Answer 3

. electrical energy is transferred into light and heat energy
.light is a useful form,heat is waste energy

Question 4

state 2 calculations to calculate efficiency

Answer 4

.useful output energy transfer/total input energy transfer

.useful power output/total power output

Question 5

how can the efficiency of a system be increased

Answer 5

1. reducing waste output, by lubrication,thermal insulation
2. Recycling waste output e.g recycling thermal waste energy as input energy.

Question 6

state the consequence for energy transfer of a material with a high thermal conductivity

Answer 6

the rate of energy transfer through the material is higher than for a material with a lower thermal conductivity.

Question 7

do double-glazed windows have a higher or lower thermal conductivity than single-glazed windows

Answer 7

lower,meaning less energy transfers through them

Question 8

what key factor affects the rate of cooling of a building

Answer 8

.the thickness of the walls
.the thermal conductivity of the walls

Question 9

state 3 methods of reducing heat loss in a building

Answer 9

. double glazing
.loft and wall insulation
.thicker walls