Types of Forces

Applied force is a push or pull exerted by an object or person onto another object. An example is Bob pushing a box forward. In free body diagrams, it's typically labeled as 'F' or 'F_app'.

Gravitational force, also known as weight force, is exerted by massive objects like planets, pulling other objects downwards. On Earth, gravity is 9.8 m/s² and gravitational force is calculated by multiplying this value by the object's mass. It's labeled as 'F_g', 'F_grav', or 'F_w' in diagrams.

Normal force is exerted on an object in contact with a stable surface. It always acts perpendicular to the surface. If an object is on a flat surface, the normal force goes straight up. If it's on an incline, the normal force is angled perpendicular to that incline. It's often written as 'F_n' or 'F_norm'.

Frictional force opposes motion and results from the interaction between two surfaces. Friction slows objects down; without it, objects would continue moving indefinitely. For example, friction between a box and the ground opposes the applied force pushing the box. It is usually denoted as 'F_f' or 'F_friction'.

Tensional force is exerted by a string, rope, wire, or cable, and acts along the line of the rope, pulling equally on objects at its opposite ends. If a person pulls a box with a rope, the tension force exerted by the person on the rope is equal to the tension force exerted by the rope on the box. It's commonly represented as 'F_t' or 'F_tens'.

These five main types of forces are fundamental for understanding physics, drawing free body diagrams, and solving related problems.