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[GCSE] physics > P1: Energy > Flashcards

P1: Energy Flashcards

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1
Q

give the equation for kinetic energy. Include units

A

1/2 mass x (velocity)^2
where:
energy = joules ( J)
mass = kg
velocity= (m/s)

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2
Q

give the equation for elastic potential energy. give units for all quantities/ involved

A

1/2 x spring constant x (extension)^2
energy: joules (J)
spring constant: (N/M)
extension: (m)

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3
Q

what is the equation for gravity potential energy? give the units for all quantities involved

A
  • mgh
  • mass x gravitational field strength x height
    energy: joules (J)
    mass: kg
    g: (N/kg)
    height: (m)
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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 Celcius/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 units for all quantities involved.

A

power = energy transferred / time
power = work done / time
energy ( J)
work done (J)
Time ( s)

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8
Q

what is the unit of power?

A

Watt (W)

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9
Q

Two motor lift the same mass through the same height. Motor A does this in half the time of Moto 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 Kinetic energy
  • Downwards: GPE is converted to KE
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11
Q

Describe the energy transfers for a bungee jumper

A
  • When the rope is slack and the person is falling the GPE is converted to KE of jumper
  • As the cord tightens, the fall is slower as KE is converted and stored as Elastic Potential energy
  • At the bottom, the rope recoils & the energy in the EPE store of the rope decreases and the jumper’s KE store increases until the rope becomes slack
  • ,the jumper’s KE store eventually decreases to 0. The jumper’s GPE increases
    throughout the ascent.
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12
Q

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

A
  • kinetic energy decreases since its converted to elastic potential energy
  • Since KE is proportional to ( velocity)*2 as KE decreases, so does velocity
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13
Q

Explain why the bungee jumper does not return to their original height

A
  • some energy was transferred to the thermal energy store of the surroundings by heating as the rope stretched and then shortened again.
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14
Q

Describe the energy transfers that occur when a moving object hits an obstacle ( e.g a car and a wall)

A
  • Initially, the car has kinetic energy causing it to move .
  • After the collision ,KE is transferred into the thermal store of the car and the wall
  • This thermal energy is dispersed into the air and surrounding materials
  • Some energy remains in the object’s kinetic store as it moves away after the collision.
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15
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
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16
Q

Describe the energy transfer that occurs when an object is accelerated by a constant force

A
  • energy is required to accelerate the object either chemical, thermal or electrical (DEPENDENT ON CONTEXT).
  • This energy will then be converted into kinetic energy (used to accelerate the object).
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17
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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18
Q

give three examples of chemical energy stores

A
  • food
  • fuel ( eg. wood, coal, petrol)
  • batteries
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19
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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20
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
21
Q

what is waste energy?

A
  • energy that is not used by the device for its desired purpose
22
Q

State two equations to calculate efficiency

A

useful output energy transfer/ total input energy transfer
useful power output/ total power input

23
Q

Describe the waste energy transfers that occur when bringing water to a boil in an electric kettle

A
  • Some energy is lost to the heat that warms the kettle itself and some is converted to sound energy
24
Q

describe the energy transfers that occur when a liquid is heated

A
  • when power is turned on and a current is flowing, the current in the electric circuit transfers energy to the heater ( does work)
  • this transfers electric energy from the power supply to the thermal energy store of the heater
  • causing the liquid temperature to increase
25
Q

Give two ways the efficiency of a system be increased

A
  1. reducing waste output ( by lubrication/thermal insulation)
  2. recycling waste output (eg recycling thermal waste energy as input energy)
26
Q

state three methods of reducing heat loss in a building

A
  1. double glazing
  2. loft and wall insulation
  3. thicker walls
27
Q

state the result of 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
28
Q

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

A

lower meaning less thermal energy transfers through them

29
Q

give two factors that affect the rate of cooling of a building

A
  • the thickness of the walls
  • the thermal conductivity of the walls
30
Q

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

A
  • lubricate any moving parts to reduce the friction and therefore energy loss due to heating
31
Q

how can the efficiency of a radiator be improved?

A
  • installing metal foil sheets behind the radiator to reflect the heat back into the room rather than it being absorbed back into the walls
32
Q

how can the efficiency of boiling water in a pan to be improved.

A
  • by placing a lid on the pan to reduce the heat loss from the top
33
Q

what is a renewable energy resource?

A
  • an energy source which can be replenished as it is being used up
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

give four examples of renewable energy resources

A
  1. Wind energy
  2. Hydro energy
  3. Tidal Energy
  4. Solar Energy
36
Q

give an example of a non-renewable energy resource

A
  • fossil fuels ( eg coal, oil and gas )
37
Q

give two advantages of generating power using gas rather than coal?

A
  1. Flexible generation: Gas power stations have short start-up times so can be switched on/off more easily
  2. Lower emissions of carbon dioxide
38
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
39
Q

Explain two environmental impacts of the burning of fossil fuels

A
  • Carbon dioxide contributes to the greenhouse effect and causes global warming
  • sulfur dioxide leads to acid rain which can damage buildings and crops
40
Q

State three advantages of nuclear power

A
  1. produces very large amounts of energy for relatively small quantities of fuel
  2. Doesn’t release greenhouse gases and so doesnt contribute to climate change
  3. low fuel costs
41
Q

State three disadvantages of nuclear power

A
  1. Produces nuclear waste which is harmful for humans and must be safely stored for centuries
  2. a non-renewable energy source
  3. risk of nuclear accidents , which have fatal consequences on humans and the environment
42
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
43
Q

Describe the energy transfers that occur when a vehicle is slowing down

A
  • When a vehicle brakes, velocity decreases as well as the vehicle’s kinetic energy.
  • The kinetic energy is transferred into heat energy by the brakes.
44
Q

give 5 disadvantages of using biofuels?

A
  • when plants are burned or decayed they release CO2
  • in order to grow biofuels, you need to destroy land which leads to problems :
  • 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
45
Q

give three 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 so are free
46
Q

give two disadvantages of hydroelectric power?

A
  • the dam may cause flooding
  • it can cost a lot to install the required infrastructure
47
Q

give three advantages of solar panels

A
  • they dont 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
48
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

[GCSE] physics (9 decks)

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