Grade 11 · Theory
Newton's third law
Newton's laws · about 3 min
Visual overview: Newton's third law1 MIN READ
2 study sections · pause after each one and recall the key ideaForces always come in pairs, acting on two different objects.
Key points- For every action there is an equal and opposite reaction.
- The pair acts on DIFFERENT objects, so they never cancel each other.
- Both forces are the same type (both gravitational, both contact).
- Name pairs precisely: "the force of the book on the table" and "the force of the table on the book".
- Action-reaction pair — two forces on two different bodies.
EXAM TIP
if two forces act on the SAME object they are not a Newton's third law pair — that is the standard trap.