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 into hole with drop of water to increase thermal contact
• record initial temperature.
• insert heater, connect to power supply and ammeter
• set p.d to 10v, and start stopwatch.
• current does work on heater, which transfers energy to thermal energy store of metal
• record temperature every min for 10 mins, ensure p.d is constant.

calculate power using P = VI
calculate energy transfer using E = Pt (s)
plot energy transferred to temperature graph. draw line of best fit
calculate shc using 1/(gradient x mass)

Question 3

unit for specific heat capacity

Answer 3

j/kg°c

Question 4

how to investigate effectiveness of different thermal insulators

Answer 4

• transfer 80cm^3 boiling water from kettle into a sealable beaker
• record initial temp and start stopwatch
• record temp every 3 mins for 15 mins
• pour out water and allow beaker to return to room temp
• repeat, wrapping beaker in different materials each time. ensure mass of water and insulator is the same
• plot table and compare

Question 6

define power

Answer 6

rate of work done/energy transferred

Question 7

when might an equation not be useful when calculating elastic potential energy

Answer 7

when limit of proportionality reached
(extension no longer directly proportionate to force applied)

Question 8

Describe the energy changes involved
when a pendulum swings

Answer 8

upward: ke converted to gpe
peak: maximum gpe, zero ke
downward: gpe converted to ke
friction from pivot and from air resistance means energy is wasted via thermal energy stores, so pendulum swings with less energy and eventually stops

Question 9

Describe the energy transfers for a bungee jumper.

Answer 9

falling: GPE is converted to KE
cord tightens: KE is converted to epe
cord recoils: epe converted to ke
ascends: ke converted to gpe

friction of air resistance means energy is wasted via thermal stores, jumper will not return to exact height

Question 10

examples for chemical energy stores

Answer 10

food, fuel, batteries

Question 11

what is waste energy

Answer 11

energy stored not for desired purpose

Question 12

what is conduction

Answer 12

where vibrating particles transfer energy to neighbouring particle

Question 13

what is convection

Answer 13

where energetic particles move away from hotter regions into cooler regions

Question 14

ways to increase efficiency

Answer 14

lubrication
insulation, eg use material of lower thermal conductivity
recycling waste output

Question 15

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

Answer 15

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

Question 16

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

Answer 16

double glaze windows
loft and wall insulation
thicker walls

all lower thermal conductivity

Question 17

how to improve efficiency of a robot with moving parts

Answer 17

lube it up

Question 18

renewable vs non renewable

Answer 18

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

Question 19

uses of energy

Answer 19

transport
electricity
heating

Question 20

examples of non renewable resources

Answer 20

fossil fuels:
coal
oil
gas

Question 21

advantages of fossil fuels

Answer 21

• reliable, provide when needed
• produce large amounts
• relatively cheap
• versatile, many uses

Question 22

disadvantages of fossil fuels

Answer 22

• emits large amount of CO2
• non renewable
• other pollutants produced eg sulfur dioxide, which causes acid rain

Question 23

examples of renewable resources

Answer 23

solar
wind
tidal

hydro electric
geothermal

bio fuel

Question 24

advantages of nuclear power

Answer 24

• no co2 emission when running
• reliable

Question 25

disadvantages of nuclear power

Answer 25

- holds highly dangerous radioactive material, risk of being released & harming people - produces large amounts of highly dangerous waste, stored for thousands of years before its safe - must be decommissioned when no longer used, extremely expensive

Question 26

how has the UK's use of coal changed

Answer 26

- abundantly used up to 1950s - then nuclear power produced 20% UK electricity by 1980 - became major producer of gas, by 2000 gas used as much as coal - study into climate change led to 2005 kyoto protocol to reduce greenhouse gas emissions

Question 27

coal vs gas

Answer 27

- gas has less co2 emission - gas power stations have short start-time during high demand, coal is very long

Question 28

advantages of renewables

Answer 28

- never run out, sustainable - no emissions while running

Question 29

disadvantages of all renewables

Answer 29

- non renewable is more efficient and economically beneficial, as it is cheaper and holds jobs - dependent of natural factors - only produce electricity, majority of uk use petrol cars (fossil fuels)

Question 30

disadvantages of renewables like solar, wind, tidal

Answer 30

- depend on natural factors, unreliable supply - non renwable is more efficient and economically beneficial, as it is cheaper and holds jobs - visually or audibly obstructive

Question 31

advantages and disadvantages of HEP

Answer 31

- very reliable - habitats destroyed from building dams and clearing for reservoirs - only useful in places with rivers, unlike uk

Question 32

advantage and disadvantages of tidal barrages

Answer 32

- very reliable - could damage wildlife

Question 33

advantages and disadvantages of wave power

Answer 33

- very reliable, good potential in uk due to extensive coastline - small scale

Question 34

advantages and disadvantages of biofuels (plant material)

Answer 34

- carbon neutral, as burning releases co2 but plants grown take in co2 - produces gas, highly used for transport - forest cleared to grow plants

Question 35

future of uk energy

Answer 35

- to combat unreliability of renewables, baseload needed to constantly supply electricity. nuclear power used, more built - during high demand, gas-fired power stations provide emergency power

Question 36

what are different compnenents measure in when calucating kinetic/gravitational/elastic energy

Answer 36

kinetic: speed m/s grav: field N/kg elastic: constant N/m all lengths in m all masses in kg

Question 37

what is work done and how can it be done

Answer 37

energy transferred from one store to another. can be mechanical (force) or electrical (current)

Question 38

how do turbines produce energy

Answer 38

they turn generators, which generate electricity

Question 39

how do fossil fuels provide energy

Answer 39

combusted to heat water, producing steam, which turns turbines

Question 40

how does falling wter, tides, and waves produce energy

Answer 40

moving water turns turbines

Question 41

how do nuclear and geothermal sources produce enrgy

Answer 41

nuclear fuels/hot rocks used to heat water, producing steam to turn turbines

Question 42

how do biofuels produce electricity

Answer 42

plant matter, ethanol, or methane can be produced, can be used in replacement to fossil fuels

Question 43

how do solar cells produce electricity

Answer 43

use thermal radiation to heat water to produce warm water for household use

Question 44

what can effect solar energy

Answer 44

light level, damage