Math Problem Statement

Consider vectors u and v. u = 8i + 3j, v = 3i + 5j (a) Find the vector projection w = projuv of vector v onto vector u. Express your answer in component form. w =

Solution

To find the vector projection w=projuv\mathbf{w} = \text{proj}_{\mathbf{u}} \mathbf{v} of vector v\mathbf{v} onto vector u\mathbf{u}, we can use the formula:

w=projuv=vuuuu\mathbf{w} = \text{proj}_{\mathbf{u}} \mathbf{v} = \frac{\mathbf{v} \cdot \mathbf{u}}{\mathbf{u} \cdot \mathbf{u}} \mathbf{u}

Given: u=8i+3j,v=3i+5j\mathbf{u} = 8\mathbf{i} + 3\mathbf{j}, \quad \mathbf{v} = 3\mathbf{i} + 5\mathbf{j}

Step 1: Calculate the dot product vu\mathbf{v} \cdot \mathbf{u}

vu=(3)(8)+(5)(3)=24+15=39\mathbf{v} \cdot \mathbf{u} = (3)(8) + (5)(3) = 24 + 15 = 39

Step 2: Calculate the dot product uu\mathbf{u} \cdot \mathbf{u}

uu=(8)(8)+(3)(3)=64+9=73\mathbf{u} \cdot \mathbf{u} = (8)(8) + (3)(3) = 64 + 9 = 73

Step 3: Compute the projection

w=3973u=3973(8i+3j)\mathbf{w} = \frac{39}{73} \mathbf{u} = \frac{39}{73} (8\mathbf{i} + 3\mathbf{j})

Step 4: Express w\mathbf{w} in component form

w=(39×873)i+(39×373)j\mathbf{w} = \left(\frac{39 \times 8}{73}\right) \mathbf{i} + \left(\frac{39 \times 3}{73}\right) \mathbf{j} w=(31273)i+(11773)j\mathbf{w} = \left(\frac{312}{73}\right) \mathbf{i} + \left(\frac{117}{73}\right) \mathbf{j}

Thus, the vector projection w\mathbf{w} is:

w=31273i+11773j\mathbf{w} = \frac{312}{73} \mathbf{i} + \frac{117}{73} \mathbf{j}

This is the vector projection of v\mathbf{v} onto u\mathbf{u} in component form.

Would you like more details or have any questions?


Here are 5 related questions:

  1. How do you calculate the magnitude of a vector?
  2. What is the geometric interpretation of a vector projection?
  3. How would you find the orthogonal projection of v\mathbf{v} onto u\mathbf{u}?
  4. Can vector projections be used in finding the angle between two vectors?
  5. How do vector projections relate to the concept of work done by a force?

Tip: Vector projections are useful in physics, especially when decomposing forces into components along specific directions.

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Math Problem Analysis

Mathematical Concepts

Vectors
Dot product
Vector projection

Formulas

Vector projection formula: \( \mathbf{w} = \frac{\mathbf{v} \cdot \mathbf{u}}{\mathbf{u} \cdot \mathbf{u}} \mathbf{u} \)

Theorems

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Suitable Grade Level

High School