motion and force lesson 10

Newton's third law

When body A exerts a force on body B, body B exerts an equal and opposite force on body A.

action–reaction forces

Pairs of forces that occur instantly when objects interact, which are always the same size, opposite in direction, and the same type of force.

contact interaction

An interaction where objects exert action-reaction forces on each other while physically touching.

distance interaction

An interaction where objects exert action-reaction forces over a distance without touching, such as gravitational attraction.

action-reaction vs balanced forces

Action-reaction forces act on different objects and are the same type; balanced forces all act on the same object and can be different types.

friction force pair

An interaction where an object pushes backward on the ground/snow, and the ground/snow pushes forward on the object with an equal force.

gravitational force pair

An interaction where the Earth pulls downward on an object, and the object's gravity pulls upward on the Earth with an equal force.

collision forces

Forces between hitting objects that are completely equal in size and opposite in direction, even if one object has a much larger mass than the other.

mass effect on force pairs

Why a small object accelerates more than the Earth from the same force; the Earth's massive mass makes its acceleration too tiny to notice.