Energy resources

1. Burning fossil fuels in a boiler: Fossil fuels (like coal, oil, or natural gas) are burned in a boiler. The burning releases heat energy.
2. Heating water to produce steam: The heat from the burning fuel is used to heat water in the boiler, converting the water into high-pressure steam.
3. Steam turning a turbine: The high-pressure steam is directed at the blades of a turbine, causing it to rotate.
4. Turbine turns a generator: The rotating turbine is connected to a generator. The generator uses electromagnetic induction to convert the kinetic energy of the turbine into electrical energy.

1. Wind energy
2. Solar energy (solar panels to heat water)

Advantage: High reliability. Nuclear power plants can operate continuously, providing a stable baseload power supply. They are not dependent on weather conditions.
Disadvantage: Environmental impact. Nuclear power plants produce radioactive waste, which needs to be stored safely for thousands of years. There is also a risk of accidents, which can release radioactive materials into the environment.

Disadvantage 1: Environmental impact. Constructing dams and reservoirs can flood large areas of land, displacing communities and destroying habitats. It also alters river ecosystems.
Disadvantage 2: Scale. Hydroelectric power generation may be limited by the amount of rainfall and the size of the river, meaning the availability is determined by weather factors.

Efficiency = (Useful Energy Output / Total Energy Input) x 100
Useful Energy Output = Potential Energy Gained = mgh = 1.0 kg * 10 N/kg * 3.0 m = 30 J
Efficiency = (30 J / 50 J) x 100 = 60%

Therefore, the efficiency of the motor is 60%.

1. Some energy is always converted into heat due to friction in moving parts or resistance in electrical circuits. This heat is usually dissipated into the surroundings.
2. Energy may be converted into sound, which is also often dissipated into the surroundings and not used for the intended purpose.

1. Wind energy: Uneven heating of the Earth's surface by the Sun creates pressure differences, driving wind.
2. Hydroelectric energy: The Sun drives the water cycle, causing evaporation and precipitation that fill reservoirs.
3. Biomass: Plants use solar energy to grow through photosynthesis.
4. Fossil fuels: Formed from the remains of ancient plants and animals that originally obtained energy from the Sun. All four correct answers: 2 marks.

Geothermal energy originates from the Earth's internal heat, primarily from radioactive decay of materials within the Earth's core and mantle, and residual heat from the Earth's formation. Solar radiation is external to the Earth and does not significantly contribute to the internal heat that drives geothermal activity. Solar heating only affects the very surface of the Earth.

Nuclear fusion.

Hydrogen nuclei (protons) fuse together under immense pressure and temperature to form helium nuclei. This fusion releases a tremendous amount of energy, primarily as electromagnetic radiation.

Nuclear fusion in the Sun releases a vast amount of energy in the form of electromagnetic radiation, including light and heat. This electromagnetic radiation travels through space and reaches the Earth. The Earth absorbs a portion of this radiation, which is then converted into other forms of energy, such as heat, which sustains life and drives various processes on Earth.

1. Fusion uses readily available isotopes of hydrogen (e.g. deuterium, tritium) as fuel, making the fuel source virtually inexhaustible compared to uranium for fission.
2. Fusion produces very little radioactive waste compared to fission, reducing the long-term storage and environmental concerns.

Fusion involves forcing positively charged nuclei (like isotopes of hydrogen) to combine. These nuclei repel each other due to the electrostatic force. Extremely high temperatures give the nuclei sufficient kinetic energy to overcome this electrostatic repulsion and get close enough for the strong nuclear force to bind them together, allowing fusion to occur. The higher the temperature, the higher the average kinetic energy of the nuclei.

Efficiency (%) = (Useful energy output / Total energy input) × 100%

Efficiency (%) = (160 J / 200 J) × 100%

Efficiency (%) = 80%

The motor is 80% efficient at converting electrical energy to kinetic energy.