Work, Energy and Power | Jamb(UTME)

Jamb(utme) key points on work, energy and power; forms of energy; conservation of energy; area under the force distance curve

Work

1. Work is done when a force causes an object to move in the direction of the force.
2. The formula for work is: $W = F \cdot d \cdot \cos\theta$, where:
   • $F$ is the force,
   • $d$ is the distance,
   • $\theta$ is the angle between the force and direction of motion.
3. Work is measured in joules (J).
4. 1 joule of work is done when a 1-newton force moves an object 1 meter in the direction of the force.
5. If the force is perpendicular to the motion, no work is done $(\cos90^\circ = 0)$.
6. Work can be positive (force and motion in the same direction) or negative (force opposes motion).
7. If there is no movement, no work is done.
8. The SI unit of work is the joule (J).
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Energy

9. Energy is the ability to do work.
10. Energy exists in different forms, such as mechanical, thermal, chemical, electrical, and nuclear.
11. The SI unit of energy is the joule (J).
12. Kinetic energy $(KE)$ is the energy of motion and is given by $KE = \frac{1}{2}mv^2$, where $m$ is mass and $v$ is velocity.
13. Potential energy $(PE)$ is stored energy and depends on position. It is given by $PE = mgh$, where:
    • $m$ is mass,
    • $g$ is gravitational acceleration,
    • $h$ is height.
14. Energy can change forms, such as from potential energy to kinetic energy and vice versa.
15. Total energy in a system is the sum of kinetic energy and potential energy.
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Power

16. Power is the rate of doing work.
17. The formula for power is $P = \frac{W}{t}$, where:
    • $W$ is work,
    • $t$ is time.
18. Power is measured in watts (W).
19. 1 watt equals 1 joule of work done per second.
20. A more powerful machine does the same amount of work in less time.
21. In real-life applications, power can describe engines, lightbulbs, or appliances.
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Forms of Energy

22. Mechanical energy includes both kinetic and potential energy.
23. Thermal energy is related to the temperature of a system and the motion of particles.
24. Chemical energy is stored in chemical bonds (e.g., in food or fuel).
25. Electrical energy is due to the flow of electric charges (electric current).
26. Nuclear energy is stored in the nucleus of atoms and released during fission or fusion.
27. Sound energy is carried by vibrations through a medium like air or water.
28. Light energy (radiant energy) travels in the form of electromagnetic waves.
29. Elastic energy is stored in stretched or compressed objects like springs or rubber bands.
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Conservation of Energy

30. The law of conservation of energy states that energy cannot be created or destroyed; it can only change form.
31. In any isolated system, the total energy remains constant.
32. Energy transformation examples:
    • A pendulum converts kinetic energy to potential energy and back.
    • A falling object converts potential energy into kinetic energy.
33. In a closed system, all energy is accounted for, even if transformed into heat or sound.
34. Friction causes mechanical energy to be converted into thermal energy.
35. In power plants, chemical energy (fuel) is transformed into thermal, mechanical, and electrical energy.
36. Solar panels convert light energy into electrical energy.
37. Conservation of energy is essential in understanding processes in physics, biology, and engineering.
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Force-Distance Curve

38. A force-distance curve shows how force varies as an object moves a certain distance.
39. The area under the force-distance curve represents the work done on the object.
40. If force is constant, the area is a rectangle: $W = F \cdot d$.
41. If force changes, the area may be a triangle or irregular shape.
42. For a triangular region, $W = \frac{1}{2}F_{max} \cdot d$.
43. The force-distance curve is useful in non-uniform motion, like stretching a spring.
44. In Hooke's law, the force to stretch a spring is proportional to the distance $(F = kx)$, and work is calculated from the triangular area.
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Applications of Work, Energy, and Power

45. Work is required to lift objects against gravity.
46. Kinetic energy increases with speed, making fast-moving objects harder to stop.
47. Potential energy is stored in objects like dams, batteries, or raised objects.
48. Power measures how quickly energy is transferred, such as in engines or power plants.
49. Understanding these concepts is essential for designing machines, vehicles, and electrical devices.
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Real-Life Examples of Energy Transformation

50. A ball thrown upward converts kinetic energy to potential energy.
51. A roller coaster transforms potential energy at the top into kinetic energy at the bottom.
52. A car engine converts chemical energy in fuel into mechanical energy for movement.
53. Hydroelectric plants convert gravitational potential energy of water into electrical energy.
54. Burning fuel in a power plant converts chemical energy into thermal energy, then mechanical, and finally electrical energy.
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Efficiency and Energy Loss

55. Efficiency measures how much input energy is converted into useful work.
56. No system is 100% efficient due to energy losses, often as heat or sound.
57. Friction reduces mechanical energy by converting it to heat.
58. Energy conservation helps design efficient machines to reduce energy waste.
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Force-Distance Curve and Work

59. The area under a linear force-distance curve is a triangle.
60. The area under a constant-force curve is a rectangle.
61. In variable forces, calculus is used to calculate the area under the curve.
62. Springs and elastic materials follow a force-distance relationship given by $W = \frac{1}{2}kx^2$, where $k$ is the spring constant.
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Practical Uses of Work and Energy

63. Work explains how levers and pulleys make lifting easier.
64. Energy transformations explain how solar panels, wind turbines, and batteries work.
65. Conservation of energy helps us understand natural processes like photosynthesis and metabolism.
66. Understanding power is critical in electrical grids, ensuring enough energy is delivered quickly.
67. Engineers use force-distance relationships to design safe and efficient machines.
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Key Points to Remember

68. Work is only done when a force causes displacement.
69. Energy is the capacity to do work, and it can change forms but is never lost.
70. The area under the force-distance curve is crucial for understanding work in variable force scenarios.
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Jamb(utme) key points on energy and society; renewable and non-renewable energy; use of energy; energy and development; global warming

Energy and Society

1. Energy is essential for daily activities like cooking, transportation, and communication.
2. Societies depend on energy to power homes, industries, and infrastructure.
3. Access to reliable energy improves the quality of life and promotes economic growth.
4. Energy shortages can lead to poverty, limited healthcare, and reduced education opportunities.
5. Modern technology, such as the internet and healthcare equipment, requires electricity to function.
6. Sustainable energy use ensures resources for future generations.
7. Energy consumption reflects the level of development and lifestyle in a society.
8. Efficient energy use can help reduce environmental damage.
9. Societies are transitioning from fossil fuels to cleaner energy to combat climate change.
10. Energy policies affect the economy, environment, and national security.
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Renewable Energy

11. Renewable energy comes from natural sources that are replenished, such as sunlight, wind, and water.
12. Examples of renewable energy include solar power, wind energy, hydropower, geothermal energy, and biomass.
13. Renewable energy reduces greenhouse gas emissions.
14. Solar panels convert sunlight into electricity, providing clean and sustainable power.
15. Wind turbines harness wind to generate electricity without polluting the environment.
16. Hydropower uses flowing water to produce energy, often through dams.
17. Geothermal energy uses heat from the Earth's interior for power and heating.
18. Biomass energy comes from organic materials like wood, crops, and animal waste.
19. Renewable energy sources are not depleted over time.
20. Investing in renewable energy creates jobs and strengthens energy security.
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Non-Renewable Energy

21. Non-renewable energy comes from sources that take millions of years to form and cannot be replaced quickly.
22. Examples of non-renewable energy include coal, oil, natural gas, and nuclear energy.
23. Fossil fuels (coal, oil, natural gas) are the most common non-renewable energy sources.
24. Non-renewable energy sources release significant greenhouse gases, contributing to climate change.
25. Burning coal and oil produces air pollution and health problems.
26. Natural gas is cleaner than coal and oil but still emits carbon dioxide.
27. Nuclear energy is a non-renewable source with low emissions but poses risks of radioactive waste and accidents.
28. Non-renewable energy is finite and will eventually run out.
29. Dependence on non-renewable energy makes societies vulnerable to price fluctuations and supply shortages.
30. Transitioning to renewable energy is essential to reduce dependence on non-renewable sources.
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Use of Energy

31. Energy is used in transportation (cars, planes), industries (factories), homes (lighting, appliances), and agriculture.
32. Industrial activities consume the largest share of global energy.
33. Transportation relies heavily on fossil fuels like gasoline and diesel.
34. Energy use in homes includes electricity for lights, heating, cooling, and electronics.
35. Agriculture uses energy for irrigation, machinery, and food processing.
36. Switching to energy-efficient appliances reduces energy consumption and costs.
37. Public transportation and electric vehicles reduce energy use and pollution.
38. Energy is also used for education, entertainment, and communication technologies.
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Energy and Development

39. Access to energy is a key driver of economic and social development.
40. Energy powers industries that create jobs and boost national economies.
41. Developing countries often face energy shortages, limiting their growth.
42. Access to clean energy improves healthcare by powering hospitals and medical devices.
43. Rural electrification enables education by providing light and powering schools.
44. Countries with abundant energy resources often have higher standards of living.
45. Renewable energy projects can bring electricity to remote and underserved areas.
46. Transitioning to clean energy supports sustainable development goals (SDGs).
47. Energy efficiency reduces costs and helps economies grow sustainably.
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Global Warming

48. Global warming refers to the Earth's rising average temperatures due to increased greenhouse gas emissions.
49. Burning fossil fuels for energy releases carbon dioxide, the main cause of global warming.
50. Switching to renewable energy and reducing energy waste can help combat global warming.
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Jamb(utme) key points on dams and energy production; nuclear energy; solar energy; energy crises; devices used in energy production

Dams and Energy Production

1. Dams are large structures built across rivers to store water in reservoirs.
2. Water stored in a dam has potential energy due to its height.
3. Dams use water flow to generate hydropower (electricity from moving water).
4. Hydropower plants convert the kinetic energy of flowing water into electricity.
5. Turbines inside the dam spin as water flows, driving generators to produce power.
6. Hydropower is a renewable and clean energy source.
7. Examples of famous dams include the Hoover Dam (USA) and the Three Gorges Dam (China).
8. Dams provide low-cost electricity after construction.
9. They help in flood control by regulating river water levels.
10. Dams can disrupt local ecosystems by altering natural river flow and affecting wildlife.
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Nuclear Energy

11. Nuclear energy comes from splitting atoms in a process called nuclear fission.
12. The most common fuel for nuclear power is uranium-235.
13. Fission releases a large amount of energy as heat, which is used to produce steam.
14. The steam drives turbines that generate electricity.
15. Nuclear power produces no greenhouse gases during operation.
16. Nuclear energy is extremely efficient, producing more energy from a small amount of fuel compared to fossil fuels.
17. It is a non-renewable energy source because uranium is finite.
18. Nuclear power plants produce radioactive waste, which must be stored safely for thousands of years.
19. Accidents at nuclear plants (e.g., Chernobyl, Fukushima) highlight safety concerns.
20. Nuclear energy can help reduce reliance on fossil fuels.
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Solar Energy

21. Solar energy comes from the sun's rays and is a renewable energy source.
22. Solar panels convert sunlight into electricity using photovoltaic (PV) cells.
23. Solar energy is clean, producing no greenhouse gas emissions.
24. It is abundant and available almost everywhere, especially in sunny regions.
25. Solar panels can be installed on rooftops, fields, or deserts.
26. Solar power works best during sunny weather and daytime.
27. Solar energy can be stored in batteries for use at night or during cloudy periods.
28. Large-scale solar farms generate electricity for cities and industries.
29. The cost of solar panels has dropped significantly, making them more accessible.
30. Solar water heaters use sunlight to heat water for homes and businesses.
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Energy Crises

31. An energy crisis occurs when the demand for energy exceeds supply.
32. Causes of energy crises include overdependence on fossil fuels, geopolitical conflicts, and natural disasters.
33. Energy crises can lead to blackouts, high fuel prices, and economic instability.
34. Fossil fuel depletion is a major factor in global energy crises.
35. Overpopulation increases energy demand, putting pressure on resources.
36. Transitioning to renewable energy can reduce the risk of energy crises.
37. Governments promote energy conservation and efficiency to manage energy shortages.
38. Investing in alternative energy sources like solar, wind, and nuclear can prevent future crises.
39. Energy crises highlight the importance of sustainable and diversified energy systems.
40. Efficient energy storage solutions, such as advanced batteries, help mitigate energy shortages.
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Devices Used in Energy Production

41. Turbines convert kinetic energy (from water, wind, or steam) into mechanical energy.
42. Generators convert mechanical energy into electricity.
43. Solar panels use photovoltaic cells to convert sunlight into electricity.
44. Wind turbines capture wind energy and turn it into electrical energy.
45. Steam engines and steam turbines generate power using heated water.
46. Hydroelectric turbines are used in dams to generate electricity from flowing water.
47. Geothermal plants use heat from the Earth's interior to produce steam for energy production.
48. Nuclear reactors split uranium atoms to generate heat for producing electricity.
49. Biomass boilers burn organic materials like wood or agricultural waste to generate heat and electricity.
50. Fuel cells generate electricity through chemical reactions between hydrogen and oxygen.
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