Definition: Balanced forces have equal magnitude but opposite directions, resulting in no change in motion.

Highlight: Unbalanced forces cause changes in motion, including speed or direction changes.

Example: An object under balanced forces either remains stationary or maintains constant velocity.

Example: Using a wooden block, newton meter, and various materials to measure friction.

Vocabulary: Newton meter - device for measuring force

Highlight: Rougher surfaces like sandpaper create greater frictional forces.

Definition: A force is a push or pull acting on an object that can cause changes in motion or shape.

Highlight: Forces always act in opposing pairs, following Newton's Third Law.

Example: Contact forces include friction, tension, and reaction forces, while non-contact forces include gravity, magnetic, and electrostatic forces.