A force is a push or pull on an object.

Forces can cause objects to start moving, stop moving, or change direction.

Friction is a force that opposes motion between two surfaces.

Gravity is a force that pulls objects toward each other.

Balanced forces keep an object still or moving at a constant speed.

Unbalanced forces cause acceleration or deceleration.

The stronger the force, the more it can change an object’s motion.

Force is measured in Newtons (N).

Air resistance is a type of friction that acts on objects moving through air.

Tension is a force that acts in ropes or cables when they are pulled tight.