Vector Analysis in Mixed Reference Frames

00:00 10 marks

  • Exam Style - Paper 3
  • HL
  • Tier 4
  • Vector components
  • Coordinate transformations
  • Mixed reference frames

Consider a vector \(\vec{v}\) defined in a 2D coordinate system as \(\vec{v} = (3, 4)\).

(a) Express \(\vec{v}\) in polar coordinates and calculate its magnitude and direction.

(b) Now, extend this vector to a 3D coordinate system by assigning a \(z\)-component of 5. Write the new vector \(\vec{v_3}\) in component form, and determine its magnitude.

(c) Discuss how the vector transformation from 2D to 3D changes the interpretation of its components and what challenges arise in mixed reference frames.

Part a

5 minutes 3 marks

Question

Express \(\vec{v} = (3, 4)\) in polar coordinates by finding its magnitude and direction (angle measured from the positive x-axis).



Hint Hint

Hint

Recall that \(r = \sqrt{x^2 + y^2}\) and \(\theta = \tan^{-1}(y/x)\).

  • Answer Answer

Complete Answer

Magnitude: 5; Direction: \(\theta = \tan^{-1}(\frac{4}{3})\) (approximately \(53.13^\circ\))

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Part b

5 minutes 3 marks

Question

Extend the 2D vector \(\vec{v}\) to 3D by adding a \(z\)-component of 5, forming \(\vec{v_3} = (3, 4, 5)\). Calculate its magnitude.



Hint Hint

Hint

Use the 3D magnitude formula: \(\sqrt{x^2 + y^2 + z^2}\).

  • Answer Answer

Complete Answer

Magnitude: \(\sqrt{3^2 + 4^2 + 5^2} = \sqrt{9+16+25} = \sqrt{50} \approx 7.07\)

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Part c

5 minutes 4 marks

Question

Discuss the impact of extending a 2D vector into 3D on the interpretation of its components and the challenges that may arise when working in mixed reference frames.



Hint Hint

Hint

Consider the additional complexity introduced by the third dimension and issues in coordinate transformation.

  • Answer Answer

Complete Answer

Extending a 2D vector to 3D adds an extra component that complicates the analysis of its direction and magnitude. This introduces challenges in ensuring consistent reference frames and managing rotations or transformations between coordinate systems.

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