Mathematics
Grade 10
15 min
Graph a resultant vector using the triangle method (Tutorial Only)
Graph a resultant vector using the triangle method (Tutorial Only)
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1
Introduction & Learning Objectives
Learning Objectives
Define a vector and identify its magnitude and direction.
Accurately identify the 'head' and 'tail' of a vector arrow.
State and apply the 'head-to-tail' rule for graphical vector addition.
Construct a resultant vector for two given vectors using a ruler and protractor.
Draw the resultant vector from the tail of the first vector to the head of the second vector.
Determine the magnitude and direction of a resultant vector from a scale drawing.
Interpret the meaning of a resultant vector in a simple context, such as displacement or force.
Imagine you walk 5 blocks east, then 4 blocks north. How would you describe your final position relative to where you started? 🗺️ Vectors give us the tools to answer this precisely!
This tu...
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Key Concepts & Vocabulary
TermDefinitionExample
VectorA quantity that has both magnitude (size) and direction. It is represented graphically by an arrow.A displacement of 10 km North. The magnitude is 10 km, and the direction is North.
ScalarA quantity that has only magnitude, but no direction.A distance of 10 km. We know how far, but not in which direction.
MagnitudeThe length or size of a vector. It is always a positive scalar value.For a velocity vector of 60 km/h East, the magnitude is 60 km/h.
DirectionThe orientation of a vector in space, often expressed as an angle from a reference line or a compass bearing.For a force vector of 25 N at 30° above the horizontal, the direction is 30° above the horizontal.
Resultant VectorThe vector sum of two or more vectors. It represents the single vector that would have t...
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Core Formulas
Vector Addition Notation
\vec{R} = \vec{A} + \vec{B}
This is the mathematical expression for adding vector A and vector B to get a resultant vector R. The arrow above each letter signifies that it is a vector quantity.
Triangle Method (Head-to-Tail Rule)
To add \vec{A} and \vec{B}, place the tail of \vec{B} on the head of \vec{A}.
This is the fundamental rule for graphical vector addition. You draw the first vector, and then start drawing the second vector where the first one ended. The vectors are drawn one after another in a chain.
Drawing the Resultant
The resultant \vec{R} is drawn from the tail of the first vector (\vec{A}) to the head of the last vector (\vec{B}).
After arranging the vectors head-to-tail, the resultant 'closes the triangle'. It repres...
4 more steps in this tutorial
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Challenging
Consider the vector addition \vec{R} = \vec{A} + \vec{B}. If you were to instead add the vectors in the opposite order, \vec{S} = \vec{B} + \vec{A}, using the triangle method, how would the resultant vector \vec{S} compare to \vec{R}?
A.\vec{S} is identical to \vec{R} in both magnitude and direction.
B.\vec{S} has the same magnitude as \vec{R} but the opposite direction.
C.\vec{S} has the same direction as \vec{R} but a different magnitude.
D.The relationship cannot be determined graphically.
Challenging
A boat travels 12 km East, then 9 km North. A student uses a scale of 1 cm = 3 km. They draw the vectors and the resultant, then measure the resultant's length on their paper. What should the length be, and what is the magnitude of the boat's total displacement?
A.Length = 7 cm; Magnitude = 21 km
B.Length = 5 cm; Magnitude = 15 km
C.Length = 5 cm; Magnitude = 21 km
D.Length = 7 cm; Magnitude = 15 km
Challenging
A student correctly draws two perpendicular vectors, \vec{A} and \vec{B}, and their resultant \vec{R}, forming a right-angled triangle. They use a protractor to measure the angle between vector \vec{A} and the resultant \vec{R} (the angle at the tail of \vec{A}). What does this angle represent?
A.The magnitude of the resultant vector.
B.The sum of the angles of the two vectors.
C.An error in their drawing, as this angle is irrelevant.
D.The direction of the resultant vector, relative to the direction of vector \vec{A}.
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