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Physics AQA GCSE (Separate) > 1: Energy > Flashcards

1: Energy Flashcards

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1
Q

thing can only do work if they…

A

contain a store of energy

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2
Q

what is a kinetic energy store?

A

the energy of a moving object

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3
Q

what is a gravitational potential energy store?

A

the energy something gains when you lift it up; lost when it falls

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4
Q

what is an elastic potential energy store?

A

the energy of a stretched spring or elastic band

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5
Q

what is an electrostatic energy store?

A

the energy due to the force of attraction / repulsion between two charges

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6
Q

what is a magnetic energy store?

A

the energy due to the force of attraction / repulsion between two magnets

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7
Q

what is a chemical energy store?

A

the energy contained in a chemical substance

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8
Q

what is a nuclear energy store?

A

the energy contained within the nucleus of an atom

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9
Q

what is a thermal energy store?

A

the energy something has due to its temperature / state

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10
Q

in what four ways can energy be transferred?

A

mechanically - when a force acts on a body, energy transferred between two stores
electrically - electricity can transfer energy from a power source, delivering it to components in a circuit
heating - thermal energy transferred by conduction, convection and thermal radiation
radiation - light and sound carry energy and so can transfer it

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11
Q

what is the conservation of energy?

A

energy cannot be created or destroyed - can only be transferred from one store to another

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12
Q

what is energy like in a closed system?

A

total amount of energy is constant

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13
Q

what is the diagram to show energy changes?

A

original energy store –> new energy store –> final energy store

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14
Q

what energy does an object have when it’s moving?

A

kinetic energy

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15
Q

what’s the equation for kinetic energy?

A

KE (J)= 1/2 x mass (kg) x speed squared (m/s)

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16
Q

what energy does an object have when it is raised above ground level?

A

gravitational potential energy - energy due to height in a gravitational field

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17
Q

what’s the equation for gravitational potential energy?

A

GPE (J) = mass (kg) x height (m) x gravitational field strength (N/kg)

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18
Q

what energy does a stretched spring have?

A

elastic (store) - work done on the spring to stretch/compress is equal to the amount of energy stored

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19
Q

what’s the equation for elastic potential energy/work done on a spring (assuming the limit of proportionality has not been exceeded)?

A

energy (J) = 0.5 × spring constant (N/m) × extension squared (m)

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20
Q

what is specific heat capacity?

A

the amount of thermal energy required to raise the temperature of 1kg of that substance by 1 °C.

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21
Q

what is the equation to calculate the amount of thermal energy needed to raise the temperature of a given mass of material by a different amount?

A

change in thermal energy (J) = mass (kg) × specific heat capacity (J/kg °C) × change in temperature (°C)

22
Q

describe the experiment to determine the specific heat capacity of a substance

A

start by attaching power supply to heater & inserting heater and thermometer into a block of substance (has weight of 1kg) and measure initial temp. of substance.
turn on power supply & start stop-clock.
whilst the power supply is on take several periodic measurements of voltage & current, & calculate an average of these values.
after 5 minutes switch off the power supply, stop the stop-clock & leave apparatus for a few more minutes.
monitor thermometer & make a note of highest temp. reached.
calculate the rise in temperature.

23
Q

heat supplied to a substance can be calculated using the equation:

A

energy (J) = current (A) × voltage (V) × time (s)

24
Q

what is the issue with the practical?

A

not all of heat supplied by the heater will go into substance – some will go into surroundings & substance will also lose heat whilst it is being heated; means value for the heat added will be too great which means calculated specific heat capacity will be too great

25
Q

what is power?

A

the rate at which energy is transferred / work is done

26
Q

what is the equation to calculate power?

A

power (W) = work done (J) / time taken (s)

27
Q

two identical cars accelerating to the same final speed will gain the same amount of energy. if one of them reaches that speed sooner, who has the greater power?

A

the faster one

28
Q

what (3) forms of energy can dissipate?

A

heat, light, sound

29
Q

if energy dissipates, what does this mean?

A

becomes v. difficult to gather the energy back together again; so energy becomes less useful - wasted

30
Q

give an example of a closed system and how the net energy does not change.

A

a gas cooker, heating a pan of water, takes energy from chemical store of gas and transfers it to thermal store of water

31
Q

in what two ways can you reduce energy loss?

A

reduce amount of unwanted energy produced; prevent energy from dissipating

32
Q

how can mechanical loss of energy, due to friction be reduced?

A

amount of friction reduced, less energy will be transferred into heat - lubricate the parts that rub together

33
Q

how can you stop/reduce loss of heat energy?

A

surround something with insulation

34
Q

what does the effectiveness of insulation depend on?

A

how well the insulation conducts heat; how thick the insulation is

35
Q

describe the practical to test the effectiveness of different insulations.

A

several identical containers are taken and insulated in different ways- one container should usually be left uninsulated to act as a control
beakers are then filled with equal quantities of boiling water & temp. constantly monitored using thermometer
once the water in a beaker reaches a certain temp. (e.g. 90 °C) a stopclock is started for each beaker.
temp. readings are taken at regular intervals (e.g. every minute) for a fixed amount of time (e.g. 20 mins)
a graph can then be plotted showing how the temperature of each beaker (y-axis) changes with time(x-axis).

36
Q

what is the efficiency of a system?

A

the proportion of energy that ends up in the intended form (useful energy)

37
Q

what is the equation for calculating efficiency?

A

efficiency = useful output energy transfer / total input energy transfer
OR
efficiency = useful power output / total power input
efficiency usually given as no. between 0-1 or as a %

38
Q

describe ways you can improve the efficiency of a device.

A

have to reduce the amount of unwanted energy that is produced:
to reduce friction and therefore heat energy: add bearings to prevent components from directly rubbing together; lubricating parts
to reduce resistance and therefore heat energy: use lower resistance parts; lower the current to reduce the amount of heat produced.

39
Q

what is the definition of an energy resource?

A

large banks of energy that can be transferred into a form that can be used by society

40
Q

describe how fossil fuels can be used as an energy resource, whether it is renewable or not, and the pros and cons.

A

burning fossil fuels produces steams, which can turn turbines; non-renewable; pros: reliable, can produce large amounts of energy in fairly short notice; cons: produces significant ghgs and pollution

41
Q

describe how nuclear fuel can be used as an energy resource, whether it is renewable or not, and the pros and cons.

A

nuclear fuel is reacted, producing heat which creates steam to turn turbines; non-renewable; pros: reliable, produces no ghgs or pollution, large about of energy from small amount of fuel; cons: produces toxic radioactive waste that can take thousands of years to decay

42
Q

describe how bio-fuels can be used as an energy resource, whether it is renewable or not, and the pros and cons.

A

plant matter, ethanol or methane can be produced and used as a fuel in place of fossil fuels; renewable; pros: CO2 produced whilst burning is balanced by CO2 absorbed whilst producing; cons: can take up a lot of land and consume resources that are needed for food production

43
Q

describe how wind can be used as an energy resource, whether it is renewable or not, and the pros and cons.

A

wind turbines can be used to produce electricity; renewable; pros: no ghgs or pollution produced, land can still be used for farming; cons - not reliable, noisy, ugly, not suitable everywhere

44
Q

describe how hydroelectricity can be used as an energy resource, whether it is renewable or not, and the pros and cons.

A

uses the GPE of water stored in reservoirs to turn turbines which generates electricity; renewable; pros: reliable, can produce large amount of energy at short notice, no pollution or ghgs; cons: can involve flooding areas, destroying wildlife habitats

45
Q

describe how tidal power can be used as an energy resource, whether it is renewable or not, and the pros and cons.

A

a dam is used to trap seawater at high tide and can then be released through a turbine, generating electricity, renewable; pros: predictable, large amount can be produce at regular intervals; cons: very few suitable locations, can cause environmental harm to sea life

46
Q

describe how geothermal energy can be used as an energy resource, whether it is renewable or not, and the pros and cons.

A

heat from underground can be used to create steam which spins turbines to generate electricity; renewable; pros: reliable, stations are usually small; cons: can lead to release of harmful gases underground, few suitable locations

47
Q

describe how solar power can be used as an energy resource, whether it is renewable or not, and the pros and cons.

A

photovoltaic cells can use light to create electricity;
thermal radiation from the sun can be used to warm water passing through black pipes; renewable; pros: no ghgs or pollution produce, good for producing energy in remote locations; cons: not reliable, solar farms use up a lot of farmland

48
Q

what is meant by a renewable energy resource?

A

it is replenished at a faster rate than the rate at which it is being used; cannot run out

49
Q

what is meant by a reliable energy resource?

A

one that can produce energy at any time

50
Q

why is carbon neutral energy resources not as widely used as hoped?

A

lack public support, reliability or cannot produce sufficient energy to meet our needs

51
Q

how has energy slowly been shifted to cleaner technologies?

A

government grants - encouraged development of wind & solar farms
coal - gradually replaced with cleaner natural gas
more education on different resources

52
Q

how can we further reduce CO2 emissions?

A

more nuclear power stations will be needed to replace existing fossil fuel stations; develop a way of storing energy from unreliable sources (such as solar and wind)

Physics AQA GCSE (Separate) (5 decks)

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