Unit 1 - Energy Flashcards
Define the ‘Specific Heat Capacity’ of a substance.
The amount of energy needed to raise
the temperature of 1 kilogram of a
substance by 1 degree Celsius.
State the units for Specific Heat Capacity
J/°C/kg
Joules/Degree Celsius/Kilogram
What is the definition of ‘Power’?
The rate at which energy is transferred
(or rate at which work is done).
What is the unit of power?
Watt (W)
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?
Motor A.
The energy transferred is the same but
the time taken is less (P=E/t).
Describe the energy changes involved when a ball is
thrown upwards and then returns to its starting
position. Ignore air resistance.
● Upwards: KE is converted to GPE
● Peak: Maximum GPE, zero KE
● Downwards: GPE is converted to KE
Describe the energy transfers for a bungee jumper.
● 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
Explain why a bungee jumper slows down once the
cord begins to stretch.
● Kinetic energy decreases since it is
converted to elastic potential energy
● Since KE is proportional to (velocity)²,
as KE decreases, so does velocity.
Give examples of chemical energy stores.
● Food
● Fuel (eg. wood, coal, petrol)
● Batteries
State 4 different stores of energy.
- Kinetic Energy
- Gravitational Potential Energy
- Elastic Potential Energy
- Chemical Energy
State the law of energy conservation.
Energy cannot be created or destroyed
(it can only be transferred into different
forms).
State any changes in the total energy of a ball that
is kicked, assuming that no external forces act.
The total energy of the system remains
constant due to the conservation of
energy.
What is waste energy?
The energy that is not used by the device
for its desired purpose.
Describe the energy changes that occur
in a filament light-bulb.
● Electrical energy is transferred into
light and heat energy
● Light is a useful energy form, heat is
waste energy
How can the efficiency of a system be increased?
- Reducing waste output (by
lubrication, thermal insulation etc.) - Recycling waste output (eg. recycling
thermal waste energy as input energy)
State the consequence for energy transfer of a
material with a high thermal conductivity.
The rate of energy transfer through the
material is higher than for a material with
a lower thermal conductivity.
Do double-glazed windows have a higher or lower
thermal conductivity than single-glazed windows?
Lower, meaning less energy transfers
through them.
What key factors affect the rate of cooling of a
building?
● The thickness of the walls
● The thermal conductivity of the walls
State three methods of reducing heat
loss in a building.
- Double glazing
- Loft and wall insulation
- Thicker walls
How can the efficiency of a mechanical machine with
moving parts be improved?
Lubricate any moving parts to reduce the
friction and therefore energy loss due to
heating.
How can the efficiency of a radiator be improved?
Installing metal foil sheets behind the
radiator to reflect the heat back into the
room rather than it being absorbed into
the walls.
How can the efficiency of boiling water in a pan be
improved?
By placing a lid on the pan to reduce the
heat loss from the top.
What is a renewable energy resource?
An energy source which can be
replenished as it is being used up.
Give four examples of renewable energy resources.
- Wind Energy
- Hydro-Electricity
- Tidal Energy
- Solar Energy
Give an example of a non-renewable energy
resource.
Fossil fuels (for example coal, oil and
gas).
What are the advantages of generating power using
gas rather than coal?
● Flexible Generation: Gas power
stations have short start-up times so
can be switched on/off more readily
● Lower emissions of carbon dioxide
State two disadvantages of using renewable energy
resources to generate power.
● 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
Explain the environmental impacts of burning fossil
fuels.
● Carbon Dioxide contributes to the
greenhouse effect, and causes global
warming
● Sulphur Dioxide leads to acid rain, which
can damage buildings and crops
State three advantages of fossil fuels as an energy
resource.
- Reliable: Not dependent on external factors
so can generate power anytime - Can produce large amounts of energy for a
given quantity - Still relatively abundant, so cost-effective
State three advantages of nuclear power.
- Very large amounts of energy for relatively
small quantities of fuel - Doesn’t release greenhouse gases and so
doesn’t contribute to climate change - Low fuel costs
State three disadvantages of nuclear power.
- Produces nuclear waste which is harmful to
humans & must be safely stored for centuries. - Non-Renewable energy source
- Risk of nuclear accidents, which have fatal
consequences on humans and the
environment
How does hydroelectric power produce energy?
● 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
What are some disadvantages of using biofuels?
● 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
What are the advantages of tidal energy sources?
● 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
What are the disadvantages of hydroelectric power?
● The dam may cause flooding
● It can cost a lot to install the required
infrastructure
What are some advantages of solar panels?
● 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
Give an example of a social factor which may act as
a deterrent for certain types of energy production.
● Visual Pollution
● Sound Pollution
