Nano PHYSICS . MECHANICS . MOMENTUM AND COLLISIONS . MOMENTUM CONSERVATION

Internal vs External Forces

Internal forces come in equal-and-opposite pairs and do not change total system momentum. External impulses can change total system momentum.

Physics · Mechanics · Momentum and Collisions · Momentum Conservation · Internal vs External Forces
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: internal vs external forces
Free
Establish when total system momentum is conserved and why the system boundary matters.
Prompt preview will appear here.
Goal: define the conditions for conservation of momentum using system momentum and external impulse.
STEP 2
Conceptual grounding: build the conservation model
Free
Build a workflow for systems, internal/external forces, external impulse, signs, and components.
Prompt preview will appear here.
Goal: decide whether a chosen system is isolated enough for momentum conservation.
STEP 3
Real-world connection: interpret systems and interactions
Free
Apply conservation reasoning to collisions, push-offs, explosions, 1D setups, and 2D scattering.
Prompt preview will appear here.
Goal: explain internal versus external forces, 1D conservation, and 2D component conservation in physical contexts.
STEP 4
Check your understanding: diagnostic mini-quiz
Paid
Attempt each question before revealing the momentum-conservation reasoning.
Prompt preview will appear here.
Goal: identify and correct boundary, external-impulse, internal-force, sign, and component errors before they become calculation errors.
STEP 5
Practice: solve increasingly rich momentum-conservation situations
Paid
Apply the model to situations that grow in complexity.
Prompt preview will appear here.
Goal: write concise, physically justified momentum-conservation calculations and explanations.
STEP 6
Summary & reflection + explorations
Paid
Consolidate the model and explore changing systems, external impulses, signs, and component equations.
Prompt preview will appear here.
🔒 ▶ Explore interactive simulation
Goal: carry the model forward into collisions, explosions, recoil, 2D scattering, and center-of-mass reasoning.