Energy Transfers And Resources Flashcards
What is the principle of conservation of energy?
Energy can be transferred usefully, stored, or dissipated, but it cannot be created or destroyed.
Give an example of energy transfers in a closed system.
A pendulum swinging in a vacuum, where energy transfers between kinetic energy store and gravitational potential energy store with no net change to total energy.
What is meant by dissipated energy?
Energy that is transferred to the surroundings, often as thermal energy, and is less useful.
How can unwanted energy transfers be reduced?
Through lubrication (to reduce friction) and thermal insulation (to reduce heat loss).
What is the effect of high thermal conductivity on energy transfer?
It increases the rate of energy transfer through conduction.
How does wall thickness affect the cooling of a building?
Thicker walls reduce the rate of cooling.
How does thermal conductivity affect the cooling of a building?
Lower thermal conductivity slows down energy transfer, keeping the building warmer for longer.
What is thermal insulation?
Materials or techniques used to reduce the rate of heat energy transfer.
State the two equations for efficiency.
• Efficiency = Useful output energy transfer ÷ Total input energy transfer
• Efficiency = Useful power output ÷ Total power input
How can the efficiency of an energy transfer be increased?
By reducing wasted energy transfers, such as friction or heat loss.
What does a high-efficiency device do?
Transfers a greater proportion of input energy into useful output energy.
What happens when the temperature of a system increases?
The temperature increase depends on the mass of the material, the specific heat capacity, and the amount of energy transferred.
State the equation linking change in thermal energy, mass, specific heat capacity, and temperature change.
ΔE = m × c × Δθ
Define specific heat capacity.
The amount of energy required to raise the temperature of 1 kilogram of a substance by 1°C.
What does a high specific heat capacity mean?
The substance requires more energy to increase its temperature.
Name the main energy resources used on Earth.
Fossil fuels (coal, oil, gas), nuclear fuel, biofuel, wind, hydroelectricity, geothermal, tidal, solar, and water waves.
What is a renewable energy resource?
A resource that is replenished at the same rate it is used.
Name three renewable energy resources.
Solar power, wind power, tidal energy.
Name three non-renewable energy resources.
Coal, oil, and natural gas.
What are three main uses of energy resources?
Transport, electricity generation, and heating.
Give examples of energy resources used for transport.
Petrol or diesel for vehicles (fossil fuels), biofuels for some vehicles.
Give examples of energy resources used for heating.
Gas for home heating, solar panels for water heating, and geothermal energy.
Why are some energy resources more reliable than others?
Resources like coal and nuclear provide constant supply; solar and wind depend on weather conditions.
What is the environmental impact of burning fossil fuels?
Release of carbon dioxide (leading to global warming) and sulfur dioxide (causing acid rain).
