Motion and forces form the foundation of mechanics. Displacement describes the change in an object's position, while velocity measures how quickly this position changes. Acceleration tells us how velocity itself changes over time. Newton's three laws govern all motion: objects at rest stay at rest unless acted upon by a force, force equals mass times acceleration, and every action has an equal and opposite reaction.
Energy and work are fundamental concepts in physics. Kinetic energy is the energy of motion, calculated as one-half mass times velocity squared. Potential energy is stored energy, such as gravitational potential energy equal to mass times gravity times height. Work is force applied over a distance. The pendulum demonstrates energy conservation as kinetic and potential energy transform into each other while total mechanical energy remains constant.
Heat and temperature are related but different concepts. Temperature measures the average kinetic energy of molecules, while heat is the energy transferred between objects. Heat transfer occurs through three methods: conduction through direct contact, convection through fluid motion, and radiation through electromagnetic waves. As we heat a substance, molecular motion increases, raising the temperature according to the specific heat capacity formula.
Electric circuits involve the flow of electric current through conductors. Current is the flow of electric charge, voltage is the electrical potential difference that drives this flow, and resistance opposes the current. Ohm's law states that voltage equals current times resistance. In this parallel circuit, current splits between two paths, with each resistor receiving the same voltage but carrying different currents based on their resistance values.
Magnetism and electromagnetism demonstrate the deep connection between electricity and magnetism. Magnetic fields surround permanent magnets and current-carrying conductors. When a conductor moves through a magnetic field, electromagnetic induction occurs, generating an electromotive force. This principle enables electric motors to convert electrical energy to mechanical energy and generators to convert mechanical energy to electrical energy, forming the basis of modern electrical technology.