Study Notes
Energy is the capacity to do work and can be stored in various forms such as kinetic, gravitational potential, chemical, and more. Energy is transferred between stores during events and processes, and the principle of conservation of energy states that energy is neither created nor destroyed, only transformed from one type to another.
- Energy — the capacity of something to do work. Example: A book on a table has potential energy.
- Kinetic Energy — energy an object has because of its motion. Example: A moving car has kinetic energy.
- Gravitational Potential Energy — energy an object has due to its height. Example: A fruit hanging on a tree has gravitational potential energy.
- Energy Transfer — energy can be transferred by forces, electrical currents, heating, and waves. Example: A lamp emits light and heat when a current passes through it.
- Conservation of Energy — energy is neither created nor destroyed, only transformed. Example: A pendulum's energy changes between kinetic and potential energy.
- Efficiency — a measure of how much useful energy is obtained from a system. Example: Efficiency can be calculated using the formula: efficiency = useful energy output/energy input × 100%.
Exam Tips
Key Definitions to Remember
- Energy is the capacity to do work.
- Kinetic energy is the energy of motion.
- Gravitational potential energy is energy due to height.
- The principle of conservation of energy states energy is neither created nor destroyed.
Common Confusions
- Confusing energy transfer methods, such as mechanical vs. electrical.
- Misunderstanding that energy can be wasted as heat, sound, or light.
Typical Exam Questions
- What is the work done on an object when a force is applied over a distance? Work done = force × distance
- How is kinetic energy calculated? Kinetic energy = ½mv²
- How do you calculate efficiency? Efficiency = (useful energy output / energy input) × 100%
What Examiners Usually Test
- Understanding of energy conservation in different scenarios.
- Ability to calculate work done, power, and efficiency.
- Knowledge of different forms of energy and their transformations.