Mechanics is the branch of physics dealing with the motion of bodies under the influence of forces. It is divided into two main parts: kinematics and dynamics. Kinematics is concerned with describing motion, while dynamics is concerned with the forces that cause motion.

Newton's First Law states that an object remains at rest or in uniform motion unless acted upon by an external force. Newton's Second Law states that the force on an object is equal to the mass of the object multiplied by its acceleration (F = ma). Newton's Third Law states that for every action, there is an equal and opposite reaction.

Work is done when a force causes a displacement of an object. The amount of work is equal to the force times the distance moved in the direction of the force. Energy is the capacity to do work. An object can possess energy by virtue of its motion (kinetic energy) or its position (potential energy).

The principle of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another. This principle is fundamental in understanding various phenomena in physics.

Light is a form of electromagnetic radiation that is visible to the human eye. It has properties of both waves and particles. The behavior of light can be described using the wave model, which explains phenomena such as reflection, refraction, and diffraction, as well as the particle model, which explains photoelectric effects.

Reflection is the change in direction of a wavefront at an interface between two different media, such that the wavefront returns into the medium from which it originated. Refraction, on the other hand, is the change in direction of wave propagation due to a change in its transmission medium.

Diffraction is the bending of waves around obstacles and the spreading out of waves past small openings. Interference is the phenomenon that occurs when two waves meet while traveling along the same medium. The principle of superposition governs how waves interfere with each other.