OCR · GCSE · Physics

    Course version: J249 · Version from Sept 2018

    Use vector diagrams to illustrate resolution of forces, a net force…

    Full specification wording

    Newton's laws: use vector diagrams to illustrate resolution of forces, a net force (resultant force), and equilibrium situations (to include: scale drawings limited to parallel and perpendicular vectors only) (Higher tier only)

    Higher tier learners use vector diagrams to show three situations: resolving a force into components, finding a net (resultant) force, and showing equilibrium.

    Checked against the OCR J249 specification (opens in a new tab) on .

    • Point 9 of 20
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Higher tier learners use vector diagrams to show three situations: resolving a force into components, finding a net (resultant) force, and showing equilibrium. Scale drawings are limited to parallel and perpendicular vectors, so you draw arrows to scale along two perpendicular directions. To resolve a force, draw it as the diagonal of a rectangle and read the two perpendicular components from the sides. To find a net force, add parallel vectors tip to tail and combine perpendicular ones with a right-angled triangle, measuring the resultant with a ruler and protractor. Equilibrium occurs when vectors close to form a complete shape, giving zero resultant. For example, a 5 N force at an angle resolves into a horizontal and a vertical component whose lengths you measure against the scale. Keep the scale consistent and state it on the diagram.

    What earns the marks

    • Draws vectors to a stated scale with arrows showing magnitude and direction.
    • Resolves a single force into two perpendicular components using a rectangle or right-angled triangle.
    • Adds parallel vectors tip to tail to find their combined effect.
    • Combines perpendicular vectors with a right-angled triangle to find the net force.
    • Measures the resultant with a ruler and protractor and converts using the scale.
    • Shows equilibrium by vectors forming a closed shape with zero resultant.

    Common mistakes and how to put them right

    • Draws vectors without a stated scale.

      Put it right: Label the scale so lengths can be converted to newtons.

    • Resolves a force along directions that are not perpendicular.

      Put it right: Use perpendicular components only as the specification limits.

    • Adds perpendicular vectors by simple arithmetic.

      Put it right: Combine them geometrically with a right-angled triangle.

    • Leaves a vector diagram open when forces balance.

      Put it right: Close the shape to show zero resultant in equilibrium.

    Exam tips

    • Write the scale on the diagram before drawing any vector.
    • Use a sharp pencil, ruler and protractor so measured lengths and angles are reliable.
    • State whether the situation shows resolution, a net force or equilibrium, then justify it from the diagram.

    Try the lesson

    The start of the Newton's laws: use vector diagrams to illustrate resolution of forces, a net force (resultant force), and equilibrium situations (to include: scale drawings limited to parallel and perpendicular vectors only) (Higher tier only) lesson, made from checked teaching notes for this specification point.

    Have a go first

    Two forces act on a point at right angles: 6 N to the east and 8 N to the north. Using a scale drawing or calculation, what is the magnitude of the resultant force?

    Listen

    Higher tier learners use vector diagrams to show three situations: resolving a force into components, finding a net (resultant) force, and showing equilibrium. Scale drawings are limited to parallel and perpendicular vectors, so you draw arrows to scale along two perpendicular directions. To resolve a force, draw it as the diagonal of a rectangle and read the two perpendicular components from the sides. To find a net force, add parallel vectors tip to tail and combine perpendicular ones with a right-angled triangle, measuring the resultant with a ruler and protractor. Equilibrium occurs when vectors close to form a complete shape, giving zero resultant. For example, a 5 N force at an angle resolves into a horizontal and a vertical component whose lengths you measure against the scale. Keep the scale consistent and state it on the diagram. A strong answer earns marks for these points. Draws vectors to a stated scale with arrows showing magnitude and direction. Resolves a single force into two perpendicular components using a rectangle or right-angled triangle. Adds parallel vectors tip to tail to find their combined effect. Combines perpendicular vectors with a right-angled triangle to find the net force. Exam tip: Write the scale on the diagram before drawing any vector.

    See it

    A top-down flowchart. The first node says to state the scale on the diagram, and it leads to a node saying to draw vectors to scale with arrows for magnitude and direction. From that node three branches go out. The first branch goes to resolution: draw the force as the diagonal of a rectangle, then read the two perpendicular components from the sides. The second branch goes to net force: add parallel vectors tip to tail, then combine perpendicular vectors with a right-angled triangle, then measure the resultant with a ruler and protractor and convert using the scale. The third branch goes to equilibrium: vectors close to form a complete shape, and a closed shape gives zero resultant.
    It shows the three vector diagram situations — resolving a force, finding a net force, and equilibrium — and the steps for each.

    Key words

    Say what each word means before you turn the card.

    Vector diagrams

    Try answering aloud or in your head before turning the card.

    Resolution into perpendicular components

    Try answering aloud or in your head before turning the card.

    Net (resultant) force

    Try answering aloud or in your head before turning the card.

    Equilibrium with zero resultant

    Try answering aloud or in your head before turning the card.

    See every definition
    Vector diagrams
    Drawings that use arrows to a stated scale to show magnitude and direction, used to illustrate resolution of forces, a net force and equilibrium situations.
    Resolution into perpendicular components
    Drawing a force as the diagonal of a rectangle so the two perpendicular components can be read from the sides.
    Net (resultant) force
    Found by adding parallel vectors tip to tail and combining perpendicular ones with a right-angled triangle, then measuring with a ruler and protractor.
    Equilibrium with zero resultant
    Shown when vectors close to form a complete shape, giving zero resultant.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A top-down flowchart. The first node says to state the scale on the diagram, and it leads to a node saying to draw vectors to scale with arrows for magnitude and direction. From that node three branches go out. The first branch goes to resolution: draw the force as the diagonal of a rectangle, then read the two perpendicular components from the sides. The second branch goes to net force: add parallel vectors tip to tail, then combine perpendicular vectors with a right-angled triangle, then measure the resultant with a ruler and protractor and convert using the scale. The third branch goes to equilibrium: vectors close to form a complete shape, and a closed shape gives zero resultant.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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