Energy

Summary

Energy is a fundamental concept in physics, representing the ability to do work or cause change. It can be transferred between different forms but cannot be created or destroyed, as stated by the Law of Conservation of Energy.

• Kinetic Energy — energy of motion Example: A moving car has kinetic energy.
• Chemical Energy — energy stored in chemical bonds Example: Food and fuels like coal store chemical energy.
• Gravitational Potential Energy — energy due to position in a gravitational field Example: A book on a shelf has gravitational potential energy.
• Electrical Energy — energy from electric currents Example: A light bulb uses electrical energy to produce light.
• Heat Energy — energy transferred due to temperature difference Example: Heat from a stove warms a pot of water.
• Light Energy — energy that travels in waves and can be seen Example: Sunlight is a form of light energy.
• Elastic Potential Energy — energy stored when objects are stretched or compressed Example: A stretched rubber band has elastic potential energy.

Exam Tips

Key Definitions to Remember

• Energy is the ability to do work or cause change.
• The Law of Conservation of Energy states that energy cannot be created or destroyed, only transformed.

Common Confusions

• Confusing energy with a physical substance.
• Misunderstanding that energy can be lost, rather than transformed into non-useful forms.

Typical Exam Questions

• What is kinetic energy? Energy of motion.
• How does a car engine demonstrate energy transfer? It converts chemical energy in fuel to kinetic energy.
• What happens to energy in an inefficient light bulb? It is mostly converted to heat energy, which is wasted.

What Examiners Usually Test

• Understanding of different forms of energy and examples.
• Ability to explain energy transfer and conservation.
• Identifying useful and wasted energy in energy transfer diagrams.