Nano PHYSICS . MECHANICS . DYNAMICS

Forces and Interactions

Learn to describe forces as interactions, choose a system, distinguish contact from non-contact forces, and build meaningful force diagrams.

Physics · Mechanics · Dynamics · Forces and Interactions
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 / Definition: forces are interactions
Free
Build the foundational idea that a force is an interaction between objects or systems, rather than a property carried by a single object.
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Goal: identify forces as pushes or pulls produced by interactions and describe the agent and object involved.
STEP 2
Conceptual grounding: systems, surroundings, and interaction pairs
Free
Learn how choosing a system determines which forces belong in your analysis and why forces arise through interactions with the surroundings.
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Goal: define a system deliberately and distinguish forces acting on the system from the matching forces the system exerts on other objects.
STEP 3
Real-world connection: from scenes to force models
Free
Connect force ideas to familiar situations and learn why a good force model begins by naming the object of interest.
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Goal: recognize force interactions in practical situations and choose a useful system before drawing arrows.
STEP 4
Check your understanding: mini-quiz (answers hidden until you reveal)
Paid
Attempt each question before revealing the answer and explanation.
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Goal: distinguish interactions, systems, force types, and diagram choices with confidence.
STEP 5
Practice: choosing systems and drawing force models
Paid
Solve increasingly challenging situations by defining a system, naming interactions, and constructing text-based free-body diagrams.
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Goal: turn a physical situation into a disciplined force model before using equations.