Energy

Question 1

State the law of conservarion of energy?

Answer 1

Energy camnot be created or destroyed, only transferred

Question 2

Why do you need energy?

Answer 2

Breathe, move, grow

Question 3

What are the 8 energy stores?

Answer 3

Chemical - objects
Thermal - heat
Kinetic- movement
Gravitational potential
Elastic - stretch, squash
Magnetic
Electrostatic
Nuclear

Question 4

Desribe energy stores when cooking soup?

Answer 4

Cold soup - large chemical, small thermal
Hot soup - small chemical, large thermal

Question 5

Describe energy storage in a torch?

Answer 5

Object is chemical
Converts to
Battery is electrical
Bulb is thermal

Question 6

State unit of temperature vs unit of energy

Answer 6

Celsius / joules

Question 7

State 4 pathways that transfer energy?

Answer 7

Conduction, convection, radiation and mechanical

Question 8

How is energy transferred using conduction?

Answer 8

Molecules vibrate ( molecules themselves dont get warm) as they are delocalised/free to move about. These moving particles cause transfer of energy to the touching object

Question 9

How is energy transferred during convection, eg radiator or soup in saucepan?

Answer 9

The source with the energy store (liquid or gas)heats up closest to the heat source moving from one location to another. Heat rises so the colder fluid/gas moves to the bottom replacing the hot liquid or gas in a current.

Question 10

Why is metal a good conductor of heat?

Answer 10

Packed delocalised electrons.

Question 11

What is a thermal insulator?

Answer 11

A substance that retains heat and is not a good conductor eg plastic, liquid, gas

Question 12

How does a woollen jumper keep you warm in winter?

Answer 12

The jumper is made frim wool which is a good insulator as well as tge air trapped within the jumper. The body the temperature from our body is transferred to our clothing keeping the air and wool warm.

Question 13

Name 3 fossil fuels?

Answer 13

Coal, oil, gas - formed millions of years Go from fossilsed remains eg sea creatures, trees. They are non renewable.

Question 14

What does non renewable mean?

Answer 14

You cant use them again

Question 15

What is radiation?

Answer 15

Transfer of energy by electromagnetic waves eg light, infrared, microwave

Question 16

What is difference between transfer of energy of conduction/convection vs radiation?

Answer 16

Radiation doesnt need particles to transfer energy. Eg sun can travel through a vacuum.

Question 17

Give examples of infrared radiation?

Answer 17

Burning coal, sun . All man made heated objects eg heated metal, electrical appliances. All objects emit infrared eg even an ice cube. All objects absorb infrared too.

Question 18

State what happens when infrared hits a shiny surface?

Answer 18

They reflect infrared. Dark colours or matt objects absorb infrared more quivkly. Hang clothes out on the line and dark ones will be drier than light ones.

Question 19

How would you slow down energy transfer using insulation? I can account for energy dissapation during transfers.

Answer 19

Conduction - use a good thermal insulator eg plastic kettle
Convection - use materials that can trap air
Radiation - use shiny surfaces to reflect heat

Question 20

Disadvantage of using fossil fuels?

Answer 20

Coal create lots of carbon dioxide bad for environment (greenhouse gas) Other fossil fuels when burnt creates pollutants.

Question 21

What is renewable energy?

Answer 21

Energy sources that do not run out, made ny scientists. Eg wind turbines, nuclear, turbines, biomass, solar, geothermal

Question 22

How is electricity made from coal?

Answer 22

Coal is heated, which heats water to create steam, which spins the turbine. Turbine drives the generator to produce electricty. Chemical store of fuel is transferred to thermal energy.

Question 23

What is the unit of power?

Answer 23

Watts ie how much energy is transferred per second.

Question 24

How can you calculate power?

Answer 24

Power (w) = energy (kj) / time (s)

Question 25

A shower has a power rating of 10 kilo watts (kwh). A family uses the shower for one hour per day? How much would they use in one week in kwh

Answer 25

10kw x 1 hour x 7 days = 70kwh

If 10 p per kwh, how much to use the shower? £7

Question 26

How does conservation of energy apply to simple machines?

Answer 26

The easier the machine, the less energy / force required to use it eg using a screwdriver as a leverage to open a tin can ie force applied by the lever isgreater than force required by your hand

Question 27

What is equation for doing work?

Answer 27

Work done/energy (j) = effort/power (n) x distance (m)