FeaturesHow It WorksFor ParentsPricingContactLog inStart free โ€” no credit card needed โ†’

Specialist Mathematics ยท Unit 3 ยท Vectors in two and three dimensions ยท Algebra of vectors in three dimensions

Use scalar and vector projections of vectors. scalar projection of ๐’‚ on ๐’ƒ: |๐’‚| cos(๐œƒ) = ๐’‚ โ‹… ๐’ƒฬ‚ vector projection of ๐’‚ on ๐’ƒ: |๐’‚| cos(๐œƒ) ๐’ƒฬ‚ = (๐’‚ โ‹… ๐’ƒฬ‚)๐’ƒฬ‚ = (๐’‚โ‹…๐’ƒ ๐’ƒโ‹…๐’ƒ) ๐’ƒ

Practise this objective

AI-marked practice questions tied to QCAA mark schemes for this exact LO. Free to start.

Start free practice

Practice questions for this objective

Full questions, answers and worked solutions unlock when you start a free practice session.

Question 1

A loading crane has a cable extending from point P to point Q, represented by the vector **PQ** = {2, โˆ’3, 4}. A force vector **F** = {6, โˆ’2, โˆ’1} acts on the cable. (a) Calculate the scalar projection of **F** on **PQ**. Express your answer in the form \(\frac{a\sqrt{b}}{c}\) where \(a\), \(b\), and \(c\) are positive integers with \(b\) square-free. (2 marks) (b) Hence, determine the vector projection of **F** on **PQ**, expressing your answer in the form {\(p\), \(q\), \(r\)} where \(p\), \(q\), \(r\) are simple fractions. (3 marks)

Worked answer
๐Ÿ”’ Start free to see full answer
Question 2

Calculate the scalar projection of vector OP onto vector OQ.

Worked answer
๐Ÿ”’ Start free to see full answer
Question 3

Two vectors are defined as ฮฑ = (2, 3) and ฮฒ = (4, 1). Use the scalar product formula to determine the scalar projection of ฮฑ onto ฮฒ.

Worked answer
๐Ÿ”’ Start free to see full answer
Question 4

A surveyor needs to find the perpendicular distance from point $P$ to a fence line passing through the origin. The fence direction is given by vector $\mathbf{b} = \begin{pmatrix} 4 \\ 3 \\ 0 \end{pmatrix}$, and the position of $P$ relative to the origin is $\mathbf{p} = \begin{pmatrix} 6 \\ 8 \\ 0 \end{pmatrix}$. The surveyor first calculates the scalar projection of $\mathbf{p}$ onto $\mathbf{b}$ to determine the position along the fence. Which of the following is the scalar projection of $\mathbf{p}$ on $\mathbf{b}$?

Worked answer
๐Ÿ”’ Start free to see full answer
Question 5

Two vectors \(\vec{p} = [2, 1, -1]\) and \(\vec{q} = [1, 0, 1]\) are drawn from the origin as shown. Calculate the scalar projection of \(\vec{p}\) onto \(\vec{q}\), giving your answer in the form \(\frac{a}{\sqrt{b}}\) where \(a\) and \(b\) are positive integers.

Worked answer
๐Ÿ”’ Start free to see full answer
Question 6

Find the scalar projection of \(\mathbf{u} = \begin{bmatrix} 2 \\ -1 \\ 3 \end{bmatrix}\) onto \(\mathbf{v} = \begin{bmatrix} 1 \\ 2 \\ 2 \end{bmatrix}\).

Worked answer
๐Ÿ”’ Start free to see full answer
Question 7

The points T(2, โˆ’1, 3) and Q(โˆ’4, 2, 1) are joined to the origin O. Calculate the scalar projection of vector TQ onto vector OT.

Worked answer
๐Ÿ”’ Start free to see full answer
Question 8

A force **F** = \(\begin{bmatrix} 6 \\ -3 \\ 2 \end{bmatrix}\) newtons acts on an object that moves along a straight line in the direction of vector **d** = \(\begin{bmatrix} 2 \\ 2 \\ 1 \end{bmatrix}\) metres. (a) Calculate the scalar projection of **F** onto **d**. (1 mark) (b) Hence calculate the vector projection of **F** onto **d**. (2 marks)

Worked answer
๐Ÿ”’ Start free to see full answer
Unlock all 8 answers โ€” free

More in Algebra of vectors in three dimensions

โ† Previous
Use multiplication by a scalar of a vector in Cartesian form.
Next โ†’
Use the scalar (dot) product. ๐’‚ โ‹… ๐’ƒ = |๐’‚||๐’ƒ| cos(๐œƒ) ( ๐‘Ž1 ๐‘Ž2 ๐‘Ž3) โ‹… ( ๐‘1 ๐‘2 ๐‘3) = ๐‘Ž1 ๐‘1 + ๐‘Ž2 ๐‘2 + ๐‘Ž3 ๐‘3
All LOs in Algebra of vectors in three dimensionsBack to full Specialist Mathematics syllabus