P3

Question 1

explain that energy is conserved.

Answer 1

energy cannot be created nor destroyed, it can only be moved or transferred from one form to another. it only is conserved in a closed system which is where you have taken into account everything and there are no external forces like friction that might affect things later.

Question 2

give examples of energy being moved between different stores.

Answer 2

when a ball roles down a hill (kinetic energy) and then it crashes into a drum kit ( sound energy).

Question 3

what happens to “waste” energy.

Answer 3

if it is heat then it dissipates into the atmosphere around.

Question 4

how can you reduce the wasted energy in a system.

Answer 4

use high efficiency tools or machinery. reducing friction.

Question 5

define efficiency

Answer 5

the fraction of the energy supplied to a device which is transferred in a useful form.

Question 6

explain how efficiency can be increased.

Answer 6

by reducing the non useful energy out.

Question 7

what is the formula for calculating energy efficiency?

Answer 7

efficiency = useful energy out ÷ total energy in ( for a decimal efficiency, for a percentage x by 100.

Question 8

describe the ways in which energy can be transferred by heating.

Answer 8

radiation- the emission of energy as electromagnetic waves or as moving subatomic particles,
convection-the transfer of heat from one place to another by the movement of fluids ( convection currents)
conduction-Heat energy is conducted from the hot end of an object to the cold end.

Question 9

describe ways of reducing unwanted energy transfers using thermal insulation.

Answer 9

you could wrap a thermal insulating material around the object which would help retain the thermal heat energy and help reduce unwanted heat transfer.

Question 10

how does thermal insulation work?

Answer 10

it helps reduce the heat transfer through conduction, convection and radiation.

Question 11

define thermal conductivity.

Answer 11

a measure of the ability of a substance to conduct heat.

Question 12

how does the thickness and the thermal conductivity affect the rate of cooling?

Answer 12

if it has a low thermal conductivity and thick walls then it will cool more slowly and if it is the opposite then it will cool more quickly.

Question 13

how do different factors affect the gravitational potential energy stored in an object?

Answer 13

the mass will increase it and the height above the ground and the gravitational field strength.

Question 14

what is the equation for gravitational potential energy?

Answer 14

GPE= MASS X GRAVITATIONAL STRENGTH X HEIGHT.

Question 15

how do different factors affect the kinetic energy stored in an object?

Answer 15

the mass of the object and the speed it is travelling at.

Question 16

what is the equation for kinetic energy?

Answer 16

kinetic energy= 1/2 × mass × speed squared.

Question 17

what are the non-renewable resources used today?

Answer 17

coal, oil, gas and nuclear.

Question 18

what are the advantages and disadvantages of using non-renewable energy resources?

Answer 18

\+ = it makes a lot of energy, they are abundant and affordable, easier to produce and use.
- = they are running out. they release greenhouse gases into atmosphere.prices increasing as they run out.

Question 19

explain how the use of non renewable resources is changing.

Answer 19

we are using them less. therefore we are using renewable resources such as solar tidal and hydroelectric.

Question 20

list the renewable energy resources in use today.

Answer 20

tidal, wave, solar, wind, hydro electric, biomass and geothermal.

Question 21

describe the source of energy for different renewable resources.

Answer 21

for for tidal, wave and hydro electric it is water currents turning turbines. for solar it is sun. for wind it it wind. for biomass it is animal waste being burnt. for geothermal it is volcanoes.

Question 22

describe the ways in which the different energy resources are used.

Answer 22

they are used to power home appliances and cars.

Question 23

why cant we only use renewable energy resources?

Answer 23

because they are expensive to make and they don’t make enough energy for us.

Question 24

how is the use of renewable energy resources changing?

Answer 24

we are using them more. we are building more solar farm wind farms, etc.