Phy1 - Energy Flashcards
What is a system?
A group of objects
What are the 4 ways energy can be transferred?
1) Mechanically (a force moving
2) Heating
3) Electrically (charge being transferred)
4) Radiation
What is “work done” the same as?
Energy transferred
What is the unit for work done?
Joules (J)
What is the equation for kinetic energy?
Ek = ½ × m × v²
Kinetic energy = 0.5 × mass × velocity²
What are 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 enter or leave
Describe the energy changes in a falling ball
The ball’s gravitational potential energy would decrease as it came closer to the ground.
The ball’s kinetic energy would increase as it speeds up
What is specific heat capacity?
The amount of energy needed to increase 1kg of a substance by 1⁰C
What is the equation for power?
P = E ÷ T
Power = Energy transferred ÷ time
or
P = WD ÷ T
Power = Work Done ÷ time
Name the energy store in a streched or compressed spring
Elastic potential energy
What does “conservation of energy” mean?
Energy can be stored, transferred or dissipated. It 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
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?
To 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 is the equation for efficiency?
(power output)
Efficiency = Useful power output ÷ Total power output
Why are homes insulated?
To reduce heat loss
Describe how energy is transferred using conduction
• Particles vibrate more
• Particles bump into eachother
• This exchanges energy
To insulate a house, would you want the insulation to have a high or low thermal conductivity?
Low (to reduce heat loss)
What is the equation for energy transferred?
(energy output)
Energy transferred = Useful output energy transferred ÷ Total input energy transferred
List 7 renewable energy stores
• Bio-fuel
• Wind
• Hydro-electricity
• Geothermal
• Tidal
• Solar
• Water waves
List 4 non-renewable energy sources
• Coal
• Oil
• Nuclear
• Gas
What do you call energy stores that do not run out?
Renewable
Name 2 gases that can be releases when burning fossil fuels and the problems they cause to the environment
Carbon dioxide - Global warming
Sulfur dioxide - Acid rain
What are the 3 types of fossil fuels?
• Coal
• Oil
• Gas
Which 3 energy stores are not reliable?
• Wind
• Waves
• Solar
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 3 disadvantages of nuclear power
• Lots of nuclear waste is produced
• Risk of major catastrophe
• High cost of building the plant
Describe how energy 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 energy 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 COz or other
pollutants
(-) Spoils view, disturbs seabed
and marine habitats
Describe how energy 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
Srow
(-) biodiversity loss in fields
used to grow crops for biofuels
Deforestation to grow crops.
List 6 energy sources that are reliable
• Biofuels
• Fossil Fuels (coal, oil, gas)
• Nuclear
• Geothermal
• Tidal
• Hydroelectric
Describe how you would measure the specific heat capacity of a block of metal (required practical)
• Measure the mass of the metal
• 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/(m0)
