What Are the 7 Main Types of Forces?

The seven main types of forces taught in introductory physics are: gravitational (weight), normal, friction, tension, spring (elastic), applied, and air resistance (drag). These categories capture the everyday pushes and pulls that determine how objects start, stop, and move, and they are practical groupings used for analyzing problems even though, at a deeper level, most arise from the fundamental interactions of nature.

The seven forces, defined and exemplified

Below is a concise guide to each force: what it is, how it acts, typical notation or formulas used in basic physics, and a quick real-world example.

• Gravitational force (Weight): The attraction between masses; near Earth’s surface, it acts downward with magnitude W = m·g (g ≈ 9.81 m/s²). More generally, F = G·m₁·m₂/r². Example: A book’s weight pulling it toward the floor.
• Normal force: The contact force exerted by a surface perpendicular to itself, preventing interpenetration. On a flat surface at rest, N often balances weight; on an incline, N = m·g·cosθ. Example: The table pushing up on a resting laptop.
• Frictional force: A contact force resisting relative motion between surfaces. Static friction: Fₛ ≤ μₛN (adjusts up to a limit). Kinetic friction: Fₖ = μₖN. Direction opposes impending or actual motion. Example: Tires gripping the road.
• Tension: The pulling force transmitted by a taut string, rope, or cable, acting along its length. In ideal, massless cords over frictionless pulleys, tension is uniform. Example: A ceiling-mounted cord holding a hanging plant.
• Spring (elastic) force: A restoring force that follows Hooke’s law in the elastic regime: F = −k·x (k is the spring constant; x is displacement from equilibrium). Example: A compressed spring pushing a toy car forward.
• Applied force: Any external push or pull exerted by an agent (a person, a machine, another body) not otherwise categorized. It can act in any direction as specified in a problem. Example: You pushing a box across the floor.
• Air resistance (drag): A fluid force opposing motion through air (or any fluid). At higher speeds, F_d ≈ ½·ρ·C_d·A·v²; at very low speeds (small objects), drag can scale roughly with v (Stokes regime). Example: A parachute slowing a skydiver to terminal velocity.

Together, these forces combine as vectors to produce a net force, which—by Newton’s second law, F_net = m·a—determines an object’s acceleration and thus its motion.

Contact versus non-contact forces

These seven are often grouped by whether they require physical contact between objects or act at a distance. This distinction helps with free-body diagrams and identifying which interactions are possible in a given situation.

• Contact forces: Normal, friction, tension, spring, applied, and air resistance. They arise from direct interactions—surface contact, molecular bonds, or collisions with fluid molecules.
• Non-contact forces: Gravitational force (in this list). It acts across space without the bodies touching. (Electrostatic and magnetic forces are also non-contact but are typically introduced separately.)

Recognizing whether a force requires contact simplifies modeling: if two bodies are not touching and no rope or fluid interaction is present, only non-contact forces like gravity can act between them.

How these relate to the fundamental forces of nature

In modern physics, there are four fundamental interactions: gravitational, electromagnetic, strong nuclear, and weak nuclear. Of the seven everyday forces above, weight directly reflects gravity. The others—normal, friction, tension, spring, applied, and drag—are effective or emergent forces rooted in electromagnetic interactions between atoms and molecules (plus momentum exchange in fluids for drag). Strong and weak forces matter mainly in nuclear and particle-scale phenomena, not typical mechanics problems.

Common misconceptions and problem-solving tips

Students often stumble over the direction, magnitude, or conditions under which these forces act. Keep the following in mind when drawing free-body diagrams or setting up equations of motion.

• Normal force isn’t “always equal to weight”: It equals whatever is needed to prevent interpenetration, up to constraints; on ramps or in elevators, it differs from m·g.
• Friction has two regimes: Static friction adjusts up to μₛN to prevent motion; once sliding begins, kinetic friction μₖN applies and is usually smaller.
• Drag depends on speed and shape: It grows rapidly with v at everyday to high speeds (quadratic regime) and points opposite relative motion through the fluid.
• Tension pulls, not pushes: Ideal strings go slack if compressed; tension acts along the string away from the object.
• Hooke’s law has limits: Springs and materials behave linearly only within their elastic range; large deformations introduce nonlinearity or permanent set.
• “Applied force” is a placeholder: It’s not a new interaction—just a named external push/pull until you model its source in more detail.
• Weight varies with location: g differs slightly with altitude and latitude; on other planets, weight changes even though mass stays the same.

Keeping these points straight helps avoid sign errors, misidentified forces, and incorrect magnitudes in calculations.

Summary

The 7 main forces used in introductory mechanics are gravitational (weight), normal, friction, tension, spring, applied, and air resistance. They provide a practical toolkit for modeling everyday motion: gravity pulls, normal and friction arise from contact with surfaces, tension and springs transmit forces through cords and elastic elements, applied forces represent external pushes or pulls, and drag resists motion through fluids. While most of these are emergent effects of electromagnetic interactions, treating them as distinct simplifies analysis and problem solving.

What are the 7 types of forces?

2.3: Types of Forces

• Gravity.
• Tension.
• Normal (Contact) Force.
• Kinetic Friction.
• Static Friction.
• Air Resistance (Drag)
• Elastic (Spring) Force.

What are the 10 main types of forces?

What Are the Main Types of Forces in Physics?

• Contact Forces. As the name suggests, we experience contact forces only when the two objects come in contact.
• Spring Force. We all have seen and used spring in our lives.
• Applied Force.
• Air Resistance Force.
• Normal Force.
• Tension Force.
• Frictional Force.
• Non-Contact Forces.

What are the 7 contact forces?

Contact forces

• Tension. Tension is a pulling force exerted on an object by a string, rope or rod.
• Friction. When two objects slide past each other they experience friction.
• Air resistance. When an object moves through the air it experiences air resistance.
• Upthrust.
• Thrust.
• Normal reaction force.

What are the 8 types of forces?

Forces are a key part of how everything in the universe interacts.

• Magnetic force. Magnetic force is the attraction or repulsion between magnetic materials.
• Gravitational force.
• Frictional force.
• Applied force.
• Tensional force.
• Normal force.
• Spring Force.
• Electric Force.