Combined Physics - 6.1 Flashcards

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1
Q

In physics, what is a ‘system’?

A

A system is an object or group of objects

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2
Q

What changes are involved in the way energy is stored in an object projected upwards?

A

Chemical Energy → Kinetic Energy → Gravitational Potential Energy

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3
Q

What changes are involved in the way energy is stored in a moving objecting hitting an obstacle?

A

Kinetic Energy → Sound Energy / Thermal Energy

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4
Q

What changes are involved in the way energy is stored in an object accelerated by a constant force such as gravity when dropping a ball?

A

Gravitational Potential Energy → Kinetic Energy

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5
Q

What changes are involved in the way energy is stored in a vehicle slowing down?

A

Kinetic Energy → Heat Energy

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6
Q

What changes are involved in the way energy is stored bringing water to a boil in an electric kettle?

A

Electrical Energy → Thermal Energy

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7
Q

What equation is used to calculate the kinetic energy of a moving object?

A
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8
Q

How can the gravitational potential energy gained by a raised object above the ground be calculated?

A
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9
Q

What is the specific heat capacity of a substance?

A

The amount of energy required to raise the temperature of 1kg of the substance by 1oC

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10
Q

What is power?

A

The rate at which energy is transferred / the rate at which work is done

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11
Q

What are the three equations associated with power?

A
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12
Q

What energy transfer is equal to a power of 1 watt?

A

1 joule per second

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13
Q

Lifting an object takes 10’000J – machine A can do this in 50s but machine B takes 100s. Which machine is more powerful?

A

Both machines transfer the same amount of energy, but machine A is more powerful:

P = W ÷ t

Machine A has a power of 200W (10’000 ÷ 50) whilst machine B has a power of 100W (10’000 ÷ 100)

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14
Q

What is the conservation of energy principle?

A

Energy can be transferred usefully, stored or dissipated but never created or destroyed

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15
Q

What happens to the energy transfer in a closed system?

A

There is no net change to the total energy

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16
Q

When energy is transferred not all of it is transferred usefully (some energy is dissipated). What term is used to describe this dissipated energy?

A

Wasted energy

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17
Q

How does lubrication reduce unwanted energy transfers?

A

Lubrication reduces frictional forces

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18
Q

How does insulation reduce unwanted energy transfers?

A

Insulation reduces the rate of energy transfer by heating

19
Q

List some examples of insulation

A
  • Cavity wall insulation (reduces convection)
  • Loft insulation (reduces convection)
  • Double-glazed windows (reduces conduction)
  • Draught excluders (reduces convection)
20
Q

What is conduction?

A

Conduction is the process where vibrating particles transfer energy to neighbouring particles (occurring mainly in solids)

21
Q

What is convection?

A

Convection is the process where energetic particles move away from hotter regions to cooler ones (occurring in fluids)

22
Q

In terms of conduction across the material what does an increased thermal conductivity of a material cause?

A

Increased thermal conductivity of a material means a higher rate of energy transfer

23
Q

How do walls and the thermal conductivity of the material affect the rate of cooling in a building?

A

Thick walls made from a material with low thermal conductivity slows the rate of energy transfer (so the building remains warmer for longer)

24
Q

What is the equation for energy efficiency for a given energy transfer, with regard to energy input/output?

A
25
Q

What is the equation for energy efficiency for a given energy transfer, with regard to power input/output?

A
26
Q

Higher Q. How can the efficiency of an intended energy transfer be increased?

A

Insulation, lubrication of more streamlined (reducing frictional forces)

27
Q

What are the main energy resources available on Earth?

A
  • Fossil fuels
  • Nuclear fuel
  • Bio-fuel
  • Wind
  • Hydro-electricity
  • Geothermal
  • Tidal
  • Solar
  • Water waves
28
Q

List the types of fossil fuel

A
  • Coal
  • Oil
  • Gas
29
Q

What does the term non-renewable energy resource mean (and list them)?

A

Non-renewable energy resources will run out, e.g. coal, oil, natural gas and nuclear

30
Q

What does the term renewable energy resource mean (and list them)?

A

Renewable energy resources can be replenished (will never run out), e.g. solar, wind, water waves, hydro-electricity, bio-fuel, tidal and geothermal

31
Q

What uses do we have for energy resources?

A
  • Transport
  • Electricity generation
  • Heating
32
Q

Describe wind power and how it is used

A

Wind turbines are placed in exposed areas where rotating blades turn a generator producing electricity. They are non-polluting (though spoil the view / are noisy)

33
Q

Describe solar cells and how they are used

A

Solar cells generate electricity directly from sunshine. They are non-polluting (though don’t work at night)

34
Q

Describe geothermal power and how it is used

A

Geothermal power relies on naturally occurring hot rocks which heat pumped water creating steam. They cause very little damage to the environment (though there are few locations available)

35
Q

Describe hydro-electric power and how it is used

A

Hydro-electric power uses falling water (usually falling over a dam). Though this is clean energy, the construction of the dam can be extremely damaging (high levels of concrete / habitat damage etc…)

36
Q

Describe water wave power and how it is used

A

Water wave power uses wave-powered turbines around the coast generating electricity.

37
Q

Describe tidal barrages and how they are used

A

Tidal barrages are dams built across river estuaries, using the Sun and Moon’s gravity where the tide turns a turbine. Non-polluting they do change the habitat

38
Q

Describe bio-fuels and how they are used

A

Bio-fuels are made from plants and waste which are supposedly carbon neutral. Costs are high and bio-fuel crops reduce space for food crops

39
Q

What energy resources are used for transport?

A

Petrol / diesel from oil is mainly used (though coal for steam engines / bio-fuels are also used)

40
Q

What energy resources are used for heating?

A

Natural gas is mainly used for heating, though coal and electric heaters are also used. Solar water heaters are also becoming more common

41
Q

Why are non-renewable energy resources so abundantly used?

A

Non-renewables are relatively cheap and are reliable (there is enough to meet current demand)

42
Q

What environmental issues do non-renewable energy resources create?

A

Fossil fuels release CO2 into the atmosphere contributing to global warming. Acid rain is also caused, along with nuclear power potential disasters / oil spillages etc…

43
Q

What current trends in energy resource use exist at present?

A

The world currently heavily depends on fossil fuels, though people are increasing wanting to use more renewables (e.g. electric cars)

44
Q

Why is renewable energy uptake limited?

A

Currently renewable energy isn’t as reliable or cost effective as non-renewable energy. Politics of increased initial prices for renewable energy resources also often gets in the way