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Physics > 1.1. Energy > Flashcards

1.1. Energy Flashcards

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1
Q

What is a system?

A

A system is an object or group of objects

e.g. an apple

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2
Q

What happens when a system changes?

A

When a system changes, the way energy is stored changes

For example, a kettle transfers electrical energy to chemical energy

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3
Q

What is Kinetic Energy?

& formula

A
  • Kinetic energy is the the energy of a moving object

_______________________________________________

Ek = 1/2 m v2
Kinetic Energy = 1/2 x mass x velocity2
_______________________________________________

Ek in Joules
Mass in kg
Velocity in m/s

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4
Q

What is Elastic Potential Energy?

& formula

A
  • Elastic Potential Energy is the energy stored when an object is stretched or squashed

_______________________________________________

Ee = 1/2 k e2
Elastic Potential Energy = 1/2 x spring constant x extension2
_______________________________________________

Ee in Joules
Spring Constant in N/m
Extension in m

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5
Q

What is Gravitational Potential Energy?

& formula

A
  • Gravitational Potential Energy is the energy of an object when it is raised above ground level

_______________________________________________

Ep = m g h
Gravitational Potential Energy = mass x gravitaional field strength x height
_______________________________________________

Ep in Joules
Gravitaional Field Strength in N/m
Height in m

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6
Q

What is Specific Heat Capacity

A

The amount of energy needed to raise the temperature of 1kg of a substance by 1°C

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7
Q

What is the formula for calculating the amount of thermal energy stored in or released from a system as the temperature changes?

A

ΔE = m c Δθ
Change in thermal energy = mass x specific heat capacity x temperature change
_______________________________________________

Change in thermal energy in Joules
Mass in kg
Specific Heat Capacity in J / Kg (per) °C
Temperature Change in °C

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8
Q

Define Power

A

Power is the rate at which energy is transferred or the rate at which work is done

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9
Q

Formula for Power

A

Power = Energy Transferred / Time
P = E / t

Power = Work Done / Time
P = W / t
_______________________________________________

Power in Watts
Energy Transferred / Work Done in Joules
Time in Seconds

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10
Q

What is 1 watt equal to?

In terms of energy

A

1 watt = 1 joule per second

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11
Q

Give one example that illustrates the defenition of power

A

Two electric motors that both lift the same weight through the same height, but one does it faster than the other

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12
Q

What is the law of conserveration of energy?

A

Energy cannot be created or destroyed, it can only be transferred from one store to another

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13
Q

When happens to the total energy when there are energy transfers in a closed system?

A

There is no net change to the total energy

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14
Q

What is wasted energy?

A

Wasted energy is energy that is dissipated or stored in less useful ways

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15
Q

Give 3 common examples of wasted energy transfer?

A
  • heat
  • light
  • sound
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16
Q

Explain ways of reducing unwanted energy transfers

A

We can reduce unwanted energy transfers by:
- Using lubrication for friction, so less thermal energy is lost as heat
- Using thermal insulation to prevent energy dissipating into the thermal energy store of the surroundings

17
Q

What does it mean if a material has high thermal conductivity?

A

If a material has a high rate of thermal conductivity, it means it has a high rate of energy transfer by conduction across the material (it can transfer the energy easily)

18
Q

Which factors affect the rate of cooling of a building?

A
  • Thickness of the walls
  • (Low/High) Thermal conductivity of the walls
19
Q

State 3 methods of reducing heat loss in a building

A
  • Double glazing windows
  • Loft and wall insulation
  • Thicker walls
  • Aluminium foil behind radiators
20
Q

What are the 2 formulas for efficiency?

A
21
Q

How can we increase the efficiency of an intended energy transfer?

A

We can increase the efficiency of energy transfer by reducing the wasted energy output

22
Q

How can the efficiency of boiling water in a pan be improved?

A

The efficiency of boiling water in a pan can be improved by placing a lid on the pan to reduce heat loss

23
Q

How can the efficiency of a machine with moving parts be improved?

A

The efficiency of a machine with moving parts can be improved by lubricating any moving parts to reduce friction and therefore reduce energy loss due to heating

24
Q

What are the main renewable and non-renewable energy resources?

A

Non-renewable:
- Fossil Fuels (coal, oil, gas)
- Nuclear Fuel
Renewable:
- Biofuel
- Wind
- Hydro-electricity
- Geothermal
- Tidal
- Solar
- Water waves

25
Q

What is a renewable energy resource?

A

A renewable energy resource is one that is being (or can be) replenished as it is used

26
Q

ENERGY RESOURCE:

Biofuel :)

A

Biofuel is a type of fuel that is produced by burning plant materials in the place of fossil fuels

27
Q

ENERGY RESOURCE:

Geothermal energy

A

Geothermal energy uses the heat from the deep inside the Earth to create steam, by pumping water into the hot rocks, which spins turbines, producing electricity - or it can also be used directly to heat buildings

28
Q

ENERGY RESOURCE:

Hydroelectricity

A

Hydroelectricity can be generated when water stored in a resevoir flows downhill and uses GPE to turn the turbines and generate electricity

29
Q

ENERGY RESOURCE:

Wind

A

The force of the wind drives the wind turbine’s blades around, which is used to turn a generator - producing electricity

30
Q

ENERGY RESOURCE:

Tidal

A
  • Tidal power stations trap water from each high tide behind a barrage
  • The high tide can then be released into the sea through turbines, which drive generators, generating electricity
31
Q

ENERGY RESOURCE:

Solar

A

Solar power uses PV cells to absorb thermal radiation from the Sun that can then be used to heat water passing through the pipes

32
Q

ENERGY RESOURCE:

Water Waves

A

Wave Power uses the kinetic energy from waves to drive electricity generators

33
Q

Why is wind and solar energy not reliable?

A

Wind and solar enery are not reliable sources of energy as some days are not windy and some days are cloudy

34
Q

Give 4 main uses of energy resources

A
  • Transport
  • Electricity
  • Generation
  • Heating

Physics (10 decks)

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