Nano PHYSICS . MECHANICS . DYNAMICS . NEWTON'S THIRD LAW

Action–Reaction Force Pairs

For every force, there is a partner force equal in magnitude and opposite in direction. Learn the interaction model behind Newton's Third Law.

Physics · Mechanics · Dynamics · Newton's Third Law · Action–Reaction Force Pairs
Access for this nano-lesson
Unsigned visitors can show & copy prompts for Steps 1-3. Signed-in free accounts can also Run with AI for Steps 1-2. Paid accounts unlock everything (Steps 1-6 + Help prompts + AI).
Steps 1-3 Free Steps 4-6 Paid
STEP 1
Orient: define action-reaction pairs
Free
Establish Newton's Third Law as a statement about paired forces in one interaction.
Prompt preview will appear here.
Goal: state the essential properties of a Newton's Third Law force pair.
STEP 2
Conceptual grounding: build the interaction model
Free
Build a source-and-receiver method for naming both members of a force pair.
Prompt preview will appear here.
Goal: identify the two objects and the same interaction behind a pair.
STEP 3
Real-world connection: identify force pairs
Free
Apply the interaction model to contact, gravity, walking, and collision examples.
Prompt preview will appear here.
Goal: explain why paired forces do not cancel on one free-body diagram.
STEP 4
Check your understanding: diagnostic mini-quiz
Paid
Attempt each question before revealing the interaction reasoning.
Prompt preview will appear here.
Goal: identify and correct pair-matching errors before they become force-diagram errors.
STEP 5
Practice: identify increasingly rich interactions
Paid
Apply the method to force-pair scenarios that grow in complexity.
Prompt preview will appear here.
Goal: explain force pairs with precise object-and-interaction language.