Vector Addition Simulator — Head-to-Tail & Parallelogram 3D Interactive

Interactive 3D vector-addition laboratory building a head-to-tail chain and its parallelogram, with independently adjustable component vectors, add/subtract operation, animated placement, live resultant measurements, guided experiments, a model-verification bench and a knowledge-check quiz.

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About the Vector Addition Simulator

This simulator builds two free Euclidean vectors A and B in 3D, then translates B to A's tip to construct the head-to-tail sum (or difference) and the completing parallelogram. Adjust each vector's x, y and z components independently, switch between addition and subtraction, and animate the translation to see that moving an arrow's position never changes its underlying components.

What the simulator shows

• A real-time 3D view of vector A anchored at the origin, a translated second vector (B, or −B during subtraction), the resultant vector and its endpoint, a completing parallelogram guide, and the x/y/z reference frame with x and y in the ground plane and z vertical — with home view, focus-selected-part, auto-rotate, expand and toggleable labels. • Eight live controls: A's x, y and z components, B's x, y and z components (each −2 to 2), an operation selector (A + B or A − B), and a head-to-tail placement slider from 0 (common tail) to 1 (translated to A's tip). • Four actions: build head-to-tail (animate), complete construction, swap A and B, and pause placement. • Seven live metrics: result x, y and z components, result length, |A|, |B| and the angle between A and B. • A Curves & measurements tab plotting result x and y, the full model equations and snapshot measurements. • An Experiments tab with four guided scenarios (right-angle addition, cancellation, subtracting a vector, swapping operands), a model-verification bench of independent automated checks, and a timestamped event log with a copyable trial report. • A Learn & assess tab with guided lessons, a two-question knowledge-check quiz and a written scope/reference statement.

Why translating an arrow does not change the vector it represents

A free vector is defined entirely by its components — Ax, Ay, Az — not by where it happens to be drawn. Sliding the placement control from 0 to 1 moves the second arrow's tail from the shared origin to A's tip, but at every point along that animation the resultant components Rx = Ax ± Bx, Ry = Ay ± By and Rz = Az ± Bz stay exactly what they were before the translation started. At an intermediate placement value, the moving arrow's tip is not yet the resultant's endpoint — only once the translation completes does the tip land on A + B (or A − B).

Subtraction is constructed by first reversing every component of B to get −B, then chaining it head-to-tail after A exactly as with addition — which is why the simulator's violet arrow represents −B specifically during a subtraction operation, not B itself.

Cancellation, commutativity and reading the resultant

The equations panel shows R = A + B (or A − B) resolved componentwise, |R| = √(Rx² + Ry² + Rz²), and cos θ = (A·B)/(|A||B|) for nonzero vectors. When A and B are exact opposites, their sum is the zero vector — which has no unique resultant direction or defined angle, since a zero-length vector carries no orientation information.

Addition is commutative (A + B always equals B + A, as the swap-operands experiment confirms), but subtraction generally is not: B − A is the negative of A − B, so swapping the two operands in a subtraction reverses the resultant's direction. This is a free-vector model — the placement animation is a display convenience for visualizing the sum, and it never alters the underlying mathematical result.

Frequently asked questions

Does moving a vector arrow to a new position change the vector itself?

No, as long as its length and direction stay the same. A free vector is determined entirely by its components, not by where it is drawn — translating the second arrow to build the head-to-tail chain repositions it visually but leaves its x, y and z components, and therefore the computed resultant, completely unchanged.

Is vector subtraction commutative like addition?

No. Addition is commutative — A + B always equals B + A — but subtraction generally is not. B − A is the exact negative of A − B, so swapping which vector comes first in a subtraction reverses the direction of the resultant, which you can confirm directly in the swap-operands experiment.

What happens when you add two vectors that are exact opposites?

Their sum is the zero vector, and the simulator has no unique resultant direction or angle to display in that case — a zero-length vector carries no defined orientation. The cancellation experiment demonstrates this by combining equal and opposite vectors and showing the resultant collapse to zero.

What does this vector addition model not include?

This is a free Euclidean vector model: vectors are defined only by their components, with no notion of a bound application point, force line of action or physical units attached. The head-to-tail placement animation is a display construction for visualizing the sum geometrically — it does not represent a physical motion of anything in the world, and it never changes the underlying resultant computed from the components.

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