energy

Question 1

define specific heat capacity

Answer 1

the energy required to heat 1 kg of a substance by 1 degree

Question 2

what is the practical to investigate specific heat capacity

Answer 2

measure mass of the block of chosen metal.
wrap it in an insulating layer to reduce energy transferred to surroundings.
insert thermometer and record initial temperature.
insert heater, set p.d to 10v, and start stopwatch.
record temperature every min for 10 mins, ensure p.d is constant.

Question 3

unit for specific heat capacity

Answer 3

j/kg°c

Question 4

define power

Answer 4

rate of work done/energy transferred

Question 5

unit of power

Answer 5

watt

Question 6

Describe the energy changes involved
when a ball is thrown upwards and then
returns to its starting position. Ignore air
resistance.

Answer 6

upward: ke converted to gpe
peak: maximum gpe, zero ke
downward: gpe converted to ke

Question 7

Describe the energy transfers for a bungee jumper.

Answer 7

falling: GPE is converted to KE
cord tightens: KE is converted and
stored as epe
lowest: initial GPE = the epe in cord

Question 8

examples for chemical energy stores

Answer 8

food, fuel, batteries

Question 9

what is waste energy

Answer 9

energy stored not for desired purpose

Question 10

what is conduction

Answer 10

where vibrating particles transfer energy to neighbouring particle

Question 11

what is convection

Answer 11

where energetic particles move away from hotter regions into cooler regions

Question 12

ways to reduce waste energy and increase efficiency

Answer 12

lubrication
insulation
recycle waste energy

Question 13

what is the only thing that is 100% efficient and why

Answer 13

electric heaters: all energy in electrostatic energy store is transferred to thermal energy stores (useful)

Question 14

three methods to reduce rate of thermal energy loss in a building

Answer 14

double glaze windows
loft and wall insulation
thicker walls

all lower thermal conductivity

Question 15

how to improve efficiency of a robot with moving parts

Answer 15

lube it up

Question 16

renewable vs non renewable

Answer 16

renewable is replenished as it is used, whereas non renewable will run out

Question 17

examples of non renewable resources

Answer 17

fossil fuels:
coal
oil
gas

Question 18

examples of renewable resources

Answer 18

solar
wind
tidal

hydro electric
geothermal

bio fuel

Question 19

disadvantages of renewables

Answer 19

depend on natural factors, unreliable supply
non renwable is more efficient and economically beneficial

Question 20

how to use wind power and two advantages/disadvantages

Answer 20

wind turbines
- no pollution, high initial costs but minimal running costs
- spoil view, unreliable

Question 21

how to use solar power and two advantages/disadvantages

Answer 21

solar cells
- no pollution, high initial costs but minimal running costs
- only supply in daytime, unreliable

Question 22

describe geothermal power

Answer 22

underground thermal energy stores of slowly decaying radioactive elements, e.g uranium

Question 23

describe hydro electric power

Answer 23

energy from falling water
water collects in dam, released to turn a turbine which generates electricity

Question 24

describe wave power

Answer 24

wave powered turbines

Question 25

describe tidal barrages

Answer 25

uses sun and moons gravity
big dams across estuaries - when tide rises, it has to flow through the turbines

Question 26

describe bio fuels and why they are good

Answer 26

burning animal and plant waste to turn turbine
carbon neutral + fairly reliable

Question 27

cons to bio fuels

Answer 27

costly
forests cleared to grow bio fuels - deforestation, wildife,