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GCSE PHYSICS > TOPIC 1 Energy > Flashcards

TOPIC 1 Energy Flashcards

1
Q

What is the equation for kinetic energy? Give SI units for all quantities involved.

A

1⁄2 m v2

1/2 x mass x (velocity)2

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2
Q

What is the equation for elastic potential energy? Give SI units for all quantities involved.

A

1⁄2 k x2
1⁄2 x Spring Constant x (Extension)2
Energy (J), Spring Constant (N/m), Extension(m)

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3
Q

What is the equation for gravity potential energy? Give SI units for all quantities involved.

A

mgh
Mass x Gravitational Field Strength x Height

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4
Q

Define the ‘Specific Heat Capacity’ of a substance.

A

The amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius.

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5
Q

State the units for Specific Heat Capacity

A

J/°C/kg Joules/Degree Celsius/Kilogram

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6
Q

What is the definition of ‘Power’?

A

The rate at which energy is transferred (or rate at which work is done).

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7
Q

State two equations for power. Give SI units for all quantities involved.

A

power = energy transferred/time
power = work done/time

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8
Q

What is the unit of power?

A

Watt (W)

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9
Q

Two motors lift the same mass through the same height. Motor A does this in half the time of Motor B. Which dissipates the most power?

A

Motor A.
The energy transferred is the same but the time taken is less (P=E/t).

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10
Q

Describe the energy changes involved when a ball is thrown upwards and then returns to its starting position. Ignore air resistance.

A

● Upwards: KE is converted to GPE ● Peak: Maximum GPE, zero KE
● Downwards: GPE is converted to KE

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11
Q

Describe 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 Elastic Potential Energy (EPE)
● At lowest point, the jumper’s initial GPE equals the EPE stored in the cord

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12
Q

Explain why a bungee jumper slows down once the cord begins to stretch.

A

● Kinetic energy decreases since it is converted to elastic potential energy
● Since KE is proportional to (velocity)2, as KE decreases, so does velocity.

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13
Q

Give examples of chemical energy stores.

A

● Food
● Fuel (eg. wood, coal, petrol)
● Batteries

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14
Q

State 4 different stores of energy.

A
  1. Kinetic Energy
  2. Gravitational Potential Energy
  3. Elastic Potential Energy
  4. Chemical Energy
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15
Q

State the law of energy conservation.

A

Energy cannot be created or destroyed (it can only be transferred into different forms).

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16
Q

State any changes in the total energy of a ball that is kicked, assuming that no external forces act.

A

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

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17
Q

What is waste energy?

A

The energy that is not used by the device for its desired purpose.

18
Q

Describe the energy changes that occur in a filament light-bulb.

A

● Electrical energy is transferred into light and heat energy
● Light is a useful energy form, heat is waste energy

19
Q

State two equations to calculate efficiency.

A

=Useful Output Energy Transfer/Total
Input Energy Transfer
=Useful Power Output/Total Power Output

20
Q

How can the efficiency of a system be increased?

A
  1. Reducing waste output (by lubrication, thermal insulation etc.)
  2. Recycling waste output (eg. recycling thermal waste energy as input energy)
21
Q

State the consequence 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.

22
Q

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

A

Lower, meaning less energy transfers through them.

23
Q

What key factors affect the rate of cooling of a building?

A

● The thickness of the walls
● The thermal conductivity of the walls

24
Q

State three methods of reducing heat loss in a building.

A
  1. Double glazing
  2. Loft and wall insulation
  3. Thicker walls
25
Q

How can the efficiency of a mechanical machine with moving parts be improved? (Higher)

A

Lubricate any moving parts to reduce the friction and therefore energy loss due to heating.

26
Q

How can the efficiency of a radiator be improved?
(Higher)

A

Installing metal foil sheets behind the radiator to reflect the heat back into the room rather than it being absorbed into the walls.

27
Q

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

A

By placing a lid on the pan to reduce the heat loss from the top.

28
Q

What is a renewable energy resource?

A

An energy source which can be replenished as it is being used up.

29
Q

Give four examples of renewable energy resources.

A
  1. Wind Energy
  2. Hydro-Electricity
  3. Tidal Energy
  4. Solar Energy
30
Q

Give an example of a non-renewable energy resource.

A

Fossil fuels (for example coal, oil and gas).

31
Q

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

A

● Flexible Generation: Gas power stations have short start-up times so
can be switched on/off more readily
● Lower emissions of carbon dioxide

32
Q

State two disadvantages of using renewable energy resources to generate power.

A

● Output often determined by external factors (like wind speed), so supply is uncertain
● Generating power through other means is often more efficient and economically
beneficial

33
Q

Explain the environmental impacts of burning fossil fuels.

A

● Carbon Dioxide contributes to the greenhouse effect, and causes global
warming
● Sulphur Dioxide leads to acid rain, which
can damage buildings and crops

34
Q

State three advantages of fossil fuels as an energy resource.

A
  1. Reliable: Not dependent on external factors so can generate power anytime
  2. Can produce large amounts of energy for a given quantity
  3. Still relatively abundant, so cost-effective
35
Q

State three advantages of nuclear power.

A
  1. Very large amounts of energy for relatively small quantities of fuel
  2. Doesn’t release greenhouse gases and so doesn’t contribute to climate change
  3. Low fuel costs
36
Q

State three disadvantages of nuclear power.

A
  1. Produces nuclear waste which is harmful to humans & must be safely stored for centuries.
  2. Non-Renewable energy source
  3. Risk of nuclear accidents, which have fatal
    consequences on humans and the environment
37
Q

How does hydroelectric power produce energy?

A

● Rainwater collects behind a dam
● When this water is released, it is used
to turn a turbine
● This turbine turns a generator which
produces electricity

38
Q

What are some disadvantages of using biofuels?

A

When plants are burned or decay they release CO2 In order to grow biofuels, you need to destroy land which leads to problems because:
○ The land could have been natural habitats Destroying land may involve burning plants growing on it, which would release CO2
Growing biofuels reduces the land available for growing
food

39
Q

What are the advantages of tidal energy sources?

A

● They do not produce greenhouse gases
● They are quite reliable, as tides happen
twice a day
● They are cheap to run as tides are
natural, and so are free

40
Q

What are the disadvantages of hydroelectric power?

A

● The dam may cause flooding
● It can cost a lot to install the required
infrastructure

41
Q

What are some advantages of solar panels?

A

● They don’t cause harm to the environment
● They are a renewable resource
● They can be used in remote areas where
other types of energy are less accessible

42
Q

Give an example of a social factor which may act as a deterrent for certain types of energy production.

A

● Visual Pollution
● Sound Pollution
(both of these are disadvantages of wind farms)

GCSE PHYSICS (3 decks)

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