Force Types
Middle School
Definition
Categories of forces, including contact forces such as friction and applied pushes, and field forces that act at a distance such as gravity, magnetism, and electric force. Identifying the forces acting on an object is the first step in analysing its motion.
Worked examples
A book resting on a table experiences gravity (field force) pulling it down and the normal force (contact force) pushing it up.
Gravity acts without touching; the table's push requires contact between surfaces.
A magnet pulls a paperclip across a gap — magnetism is a field force acting at a distance.
The magnet and clip don't touch, yet the force acts through the space between them.
Pushing a cart applies a contact force; friction (also contact) resists the motion between the wheels and floor.
Both your push and friction require surfaces in contact to act on the cart.
Common mistakes
- Friction is a field force because it resists motion. → Friction is a contact force — it acts only between touching surfaces. Friction needs surface contact; field forces act at a distance without touching.
- Air resistance is not a real force type. → Air resistance is a contact force (fluid friction). Air molecules contact the object's surface, making air resistance a contact force.
- Tension is a field force because the string transmits force along its length. → Tension is a contact force — the string must touch the object to pull it. Tension requires the rope or string to be in contact with what it pulls.
Where you'll use it next
You'll classify force types when drawing free-body diagrams, applying Newton's laws to solve motion problems, and analyzing systems in mechanics and engineering.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026