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GCSE Physics > Topic 3: Conservation of Energy > Flashcards

Topic 3: Conservation of Energy Flashcards

1
Q

What is the equation for gravitational potential energy?

A

Mass x gravitational field strength x height

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2
Q

What is the equation for kinetic energy?

A

1/2 x mass x (velocity)^2

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3
Q

What is meant by the conservation of energy?

A

The total amount of energy in a closed system remains constant and energy cannot be made or destroyed but can change from one form to another

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4
Q

What are the changes in the total energy of a ball that is kicked, assuming that no external forces act?

A

The total energy of system remains constant due to the conservation of energy

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5
Q

What are the energy changes that occur in a filament light-bulb?

A

Electrical energy is transferred into light and heat energy then light is useful energy form and heat is waste energy

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6
Q

What are the energy transfers for a bungee jumper?

A

When falling, the GPE is converted to KE of jumper, as the cord tightens, KE is converted and stored as EPE and at lowest point, the jumper’s initial GPE equals the EPE stored in the cord

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7
Q

Why does a bungee jumper slows down once the cord begins to stretch?

A

Kinetic energy decreases since it is converted to EPE and since KE is proportional to (velocity)^2, as KE decreases so does velocity

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8
Q

What is waste energy?

A

The energy that isn’t used by the device for its desired purpose, or not converted into the desired form

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9
Q

What are two equations to calculate efficiency?

A

Useful output energy (output energy) / total input energy (power output)

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10
Q

What are the consequences for energy transfer of a material with a high thermal conductivity?

A

The rate of energy transfer through the material is higher than for a material with a lower thermal conductivity

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11
Q

Do double-glazed windows have a higher or lower thermal conductivity than single-glazed windows?

A

Lower, meaning less energy transfers through them

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12
Q

What are the three methods of reducing heat loss in a building?

A

Double glazing, loft and wall insulation and thicker walls

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13
Q

How can you reduce unwanted energy transfer in a mechanical system?

A

Reduce friction by lubricating moving parts

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14
Q

How can the efficiency of a system be increased?

A

Reducing and recycling waste output

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15
Q

What is a renewable energy resource?

A

An energy source which can be replenished as its being used up

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16
Q

What are four examples of renewable energy resources?

A

Hydro-electricity, wind, tidal and solar energy

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17
Q

What is an example of a non-renewable energy resource?

A

Fossil fuels

18
Q

What are the advantages of generating power using gas rather than coal?

A

Flexible generation and lower emissions of carbon dioxide

19
Q

What are the disadvantages of using renewable energy resources to generate power?

A

Output often determined by external factors, so supply is uncertain and renewable fuels often produce less energy energy per kg

20
Q

What are the environmental impacts of burning fossil fuels?

A

Carbon dioxide contributes to the greenhouse effect, and causes global warming and sulphur dioxide leads to acid rain, which can damage buildings and crops

21
Q

What are the advantages of fossil fuels as an energy resource?

A

Reliable, produce large amounts of energy per kg and still relatively abundant, so cost-effective

22
Q

What are the advantages of nuclear power?

A

Very large amounts of energy per kg, no greenhouse gases released, so doesn’t contribute to climate change and low fuel costs

23
Q

What are the disadvantages of nuclear power?

A

Produces nuclear waste which is harmful to humans and must be safely stored for centuries, non-renewable energy source and risk of nuclear accidents which have fatal consequences on humans and the environment

24
Q

What are some examples of social factors to consider in energy production?

A

Visual and sound pollution

25
Q

How does hydroelectric power produce energy?

A

Rainwater collects behind a dam, when this water is released it’s used to turn a turbine and this turbine turns a generator which produces electricity

26
Q

What are some disadvantages of using biofuels?

A

When plants are burned they release CO2, destroy land which is habitat destruction and CO2 released when plants are cleared and growing biofuels reduces the land available for food crops

27
Q

What are the advantages of tidal energy sources?

A

No greenhouse gases, fairly reliable and cheap to run as tides are natural so free

28
Q

What are the disadvantages of hydroelectric power?

A

The dam may cause flooding and it can cost a lot to install the required infrastructure

29
Q

What are some advantages of solar panels?

A

They don’t cause harm to the environment, renewable resources and can be used in remote areas where other energy are less accessible

30
Q

What are the energy changes in a power stations?

A

Heat energy released in the reaction heats water to make steam, steam moves the turbine, converting KE, KE turns the generator and electrical energy as the generator generates electricity

31
Q

What ways can energy of a system be changed?

A

Through work done by forces, electrical input and heating

32
Q

How can energy can changing through work done by forces?

A

A force which moves an object causes work to be done over a distance

33
Q

What equation is used to measure the work done on an object?

A

Work done = force x distance

34
Q

Why do wasteful mechanical processes cause a rise in the temperature of the surroundings?

A

They cause energy to be transferred by heating the surroundings

35
Q

What is power?

A

The rate at which energy is transferred

36
Q

What are two equations for power?

A

Power = energy transferred / time
Power = work done / time

37
Q

What is the unit of power?

A

Watt

38
Q

What is one Watt equivalent to?

A

1 Joule per second

39
Q

What is efficiency?

A

The proportion of energy that is converted usefully, rather than wasted

40
Q

What are the units of efficiency?

A

It’s expressed as a percentage

41
Q

What is the law of energy conservation?

A

Energy cannot be created or destroyed

GCSE Physics (13 decks)

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