👉 Forces are external influences that cause changes in an object's motion or state. They can be categorized into various types, including gravitational forces, normal forces, frictional forces, tension forces, and applied forces. Gravitational force acts downward due to Earth's mass, normal force is perpendicular to the surface supporting an object and equals the force pressing it into that surface (e.g., when a book rests on a table, the normal force from the table equals the weight of the book), frictional forces resist motion or changes in motion between surfaces in contact, tension forces act on objects connected by a string or cable and pull equally in opposite directions, and applied forces are external forces exerted on an object to change its motion or cause it to move in a specific direction.
