Separate Physics - P1 Energy Flashcards
In physics, what is a ‘system’?
A group of objects
What are the four ways in which energy can be transferred?
- Mechanically (by a force doing work)
- Electrically (work done by moving charge)
- Heating
- Radiation (light and sound)
What is work done the same as?
Energy transferred
What equation links kinetic energy, mass and velocity?
Ek = 0.5 x m x v2
Kinetic energy = 0.5 x mass x velocity2
Name the 8 energy stores.
- Thermal
- Kinetic
- Gravitational Potential
- Elastic Potential
- Chemical
- Magnetic
- Electrostatic
- Nuclear
What is a closed system?
A system where matter or energy cannot leave or enter.
What equation links gravitational potential energy, mass, gravitational field strength and height?
Ep = m g h
Gravitational Potential Energy = mass x gravitational field strength x height
Describe the energy changes involved in a falling ball.
The ball’s gravitational potential energy store decreases.
The ball’s kinetic energy store increases.
What are the units for work done?
Joules
What is specific heat capacity?
The amount of energy required to raise the temperature of 1 kg of the substance by 1 oC.
What equation links power, energy transferred and time?
Power = Energy Transferred / Time
(P = E/t)
What equation links power, work done and time?
Power = Work done / Time
(P = W/t)
Name the energy stored in a stretched or compressed spring.
Elastic potential energy
What does ‘conservation of energy’ mean?
Energy can be transferred, stored or dissipated, but can never be created or destroyed.
Describe the energy transfer involved in a person lifting a weight.
- The person’s chemical energy store decreases.
- The kinetic energy store of the person’s arm and the weight increases.
- The gravitational potential energy store of the person’s arm and the weight increases.
Describe the energy transfer when work is done by friction.
Kinetic energy store of the object decreases.
Thermal energy store of the surroundings increases.
A book on the top shelf has a gravitational potential energy store of 100 J. The book falls. How much energy will be in the book’s kinetic energy store as it hits the ground?
100 J
What is another name for ‘wasted’ energy?
Dissipated energy
What are lubricants used for?
Reduce friction between moving objects.
List some examples of house insulation.
- Cavity wall insulation (reduces convection)
- Loft insulation (reduces convection)
- Double-glazed windows (reduces conduction)
- Draught excluders (reduces convection)
Describe how energy is transferred by convection.
- Particles gain energy
- Particles move further apart
- The fluid becomes less dense
- Particles rise and transfer energy to other particles
- The fluid becomes more dense
- Particles fall
- A convection current is formed
What equation links efficiency, useful power output and total power input?
efficiency = useful power output / total power input
Why are homes insulated?
To reduce heat loss
Describe how energy is transferred by conduction.
- Particles vibrate more
- Particles collide with neighbouring particles
- Transferring energy
To insulate a house, would you want the insulation to have a high or low thermal conductivity?
Low thermal conductivity (to reduce heat loss)
What equation links efficiency, useful output energy transfer and total input energy transfer.
efficiency = useful output energy transfer / total input energy transfer
List seven renewable resources
- Bio-fuel
- Wind
- Hydro-electricity
- Geothermal
- Tidal
- Solar
- Water waves
Name four non-renewable resources
- Coal
- Oil
- Gas
- Nuclear
What do you call energy resources that do not run out?
Renewable
Name the two gases that can be released by burning fossil fuels and the environmental problems they cause.
Carbon dioxide – global warming
Sulfur dioxide – acid rain
Higher Q. Give three ways the efficiency of an energy transfer be increased.
- Insulation
- Lubrication
- More streamlined
List the three types of fossil fuel
- Coal
- Oil
- Gas
Name three energy resources that are not reliable.
- Wind
- Wave
- Solar
Separate Q. Describe the required practical to investigate the effectiveness of materials as thermal insulators.
- Pour boiling water into a sealed container and measure the mass of the water (keep this the same each time).
- Measure the starting temperature (keep this the same each time).
- Leave for 5 mins then measure the final temperature.
- Pour away the water and allow the container to cool back to room temperature.
- Repeat the steps above, but each time, wrap the container with a different material (e.g. foil, paper, bubble wrap).
- The best insulator will have the lowest temperature decrease.
Describe how solar cells work and give some advantages and disadvantages.
Solar cells absorb light energy and transfer it into electrical energy.
(+) Do not produce CO2
(+) Expensive to buy and install
(+) Useful in remote places – can be used on a small scale to power road signs.
(-) Not reliable – only work when sunny
(-) They do not produce electricity at night
Describe how electricity is produced using hydroelectric power and give some advantages and disadvantages.
- Water collected in a large dam/reservoir
- Water falls from a height and falls through turbines
- The turbines drive a generator that generates electricity.
(+) Doesn’t produce CO2 or other pollutants. Can immediately generate electricity to meet sudden surges in demand for electricity.
(-) High initial costs, damage to the environment, habitat loss, visual pollution.
Describe how electricity is produced using tidal power and give some advantages and disadvantages.
- A tidal barrage is built across an estuary.
- The tides are produced by the gravitational pull of the Sun and Moon.
- As the tide comes in/out, it builds up behind the barrage and is then released through the barrage at a controlled speed.
- As the water moves through, it turns turbines that turn a generator to produce electricity.
(+) reliable – two tides every day, doesn’t produce CO2 or other pollutants.
(-) high installation costs, damage to wildlife, visual pollution, prevents access to boats
Give three disadvantages of nuclear power.
- Lots of nuclear waste is produced
- Risk of major catastrophe
- High cost of building power plant
Describe how electricity is produced using geothermal power and give some advantages and disadvantages.
- Water is heated by naturally hot rocks underground.
- Water is turned into steam.
- The steam turns a turbine that drives a generator to generate electricity.
(+) Reliable, doesn’t produce CO2 or other pollutants
(-) Not many suitable locations where hot rocks are close to the surface
(-) High cost of building the power plant
Describe how electricity is produced using wave power and give some advantages and disadvantages.
Waves turn turbines that turn a generator to produce electricity (or the wave movement compresses air and the air turns the turbine).
(+) Doesn’t produce CO2 or other pollutants
(-) Spoils view, disturbs seabed and marine habitats
Describe how electricity is produced using biofuels and give some advantages and disadvantages.
Plants and animal manure are used as a fuel. They are used in a power station to heat water. The water turns to steam which turns a turbine that drives a generator and produces electricity.
(+) carbon neutral (no net increase of CO2) in atmosphere. Reliable because crops don’t take long to grow.
(-) biodiversity loss in fields used to grow crops for biofuels. Deforestation to grow crops.
List three energy resources that are reliable.
Any three from:
- Biofuels
- Fossil Fuels (coal, oil, gas)
- Nuclear
- Geothermal
- Tidal
- Hydroelectric (except in droughts)
Describe how you would measure the specific heat capacity of a block of metal (required practical).
- Measure the mass of the metal block.
- Put a thermometer into the hole in the block and measure the starting temperature of the block.
- Connect an immersion heater to a joulemeter and a power pack and place the heater into the metal block.
- Insulate the block.
- Heat the block for 5 minutes.
- Calculate the temperature change of the block.
- Read the joulemeter to calculate the energy transferred to the block.
- Calculate specific heat capacity (c) using the following equation: c = E/(mθ)
