Physics - Topic 1, Energy Flashcards
What is energy?
Energy is the capacity of a system to perform work.
Define the term ‘kinetic energy’
Kinetic energy is the energy possessed by an object due to its motion.
Define the term ‘potential energy’
Potential energy is the energy stored within an object or system due to its position, shape, or state.
What is the unit of energy?
The unit of energy is the joule (J)
State the principle of conservation of energy.
Energy can neither be created nor destroyed, only transformed from one form to another.
What is the difference between renewable and non-renewable energy sources?
Renewable energy sources can be naturally replenished within a human lifetime, such as sunlight, wind, water, biomass, and geothermal heat, while non-renewable energy sources are finite and cannot be easily replaced, including fossil fuels like coal, oil, and natural gas, as well as nuclear energy from uranium.
Give examples of renewable energy sources.
Examples of renewable energy sources include:
- Solar energy: Energy harnessed from sunlight using solar panels or solar thermal systems.
- Wind energy: Energy captured from the kinetic energy of wind using wind turbines.
- Hydropower: Energy generated from flowing or falling water, typically through dams or water turbines.
- Biomass: Energy derived from organic materials such as wood, agricultural residues, or organic waste through processes like combustion, fermentation, or gasification.
- Geothermal energy: Energy extracted from the heat stored beneath the Earth’s surface, usually by tapping into geothermal reservoirs or using heat pumps.
Give examples of non-renewable energy sources.
Examples of non-renewable energy sources include:
- Fossil fuels:
- Coal: A combustible black or brownish-black sedimentary rock formed from fossilized plants.
- Oil (petroleum): A liquid hydrocarbon mixture extracted from underground reservoirs.
- Natural gas: A gaseous hydrocarbon mixture, primarily composed of methane, extracted from underground reservoirs.
- Nuclear energy: Energy released during nuclear reactions, typically through nuclear fission of uranium or plutonium isotopes in nuclear reactors.
Describe how energy is transferred by conduction.
Conduction is the transfer of heat energy through direct contact between particles within a material or between materials in contact, without the movement of the particles themselves.
Describe how energy is transferred by convection.
Convection is the transfer of heat energy through the movement of fluids (liquids or gases) due to density differences within the fluid, creating convection currents that transport heat from hotter regions to cooler regions.
Describe how energy is transferred by radiation.
Radiation is the transfer of heat energy through electromagnetic waves, such as infrared radiation, which can travel through a vacuum and do not require a medium. It occurs when an object emits electromagnetic waves due to its temperature, and these waves are absorbed by another object, increasing its temperature.
How is efficiency calculated?
Efficiency=
Total input energy or work
Useful output energy or work
×100%
What is the efficiency of an energy transfer?
Efficiency of an energy transfer is the ratio of the useful output energy or work to the total input energy or work, expressed as a percentage.
Explain how insulation can reduce energy loss.
Insulation reduces energy loss by creating a barrier that slows down the transfer of heat between two regions of different temperatures, minimizing the amount of heat that escapes or enters a space.
What is the specific heat capacity of a substance?
The specific heat capacity of a substance is the amount of heat energy required to raise the temperature of one unit mass of the substance by one degree Celsius/Kelvin.
