Question

Difficulty: MediumScalars and Vectors

Match each displacement vector combination on the left with its corresponding resultant displacement magnitude or vector on the right.

  • A walk of 3 m3\text{ m} East followed by 4 m4\text{ m} NorthA resultant magnitude of 5 m5\text{ m}
  • A walk of 5 m5\text{ m} East followed by 12 m12\text{ m} SouthA resultant magnitude of 13 m13\text{ m}
  • A walk of 8 m8\text{ m} East followed by 6 m6\text{ m} WestA resultant displacement of 2 m2\text{ m} East
  • A walk of 9 m9\text{ m} North followed by 12 m12\text{ m} EastA resultant magnitude of 15 m15\text{ m}

Answer

The correct pairs correspond as follows: 3 m3\text{ m} East and 4 m4\text{ m} North matches a resultant magnitude of 5 m5\text{ m}; 5 m5\text{ m} East and 12 m12\text{ m} South matches a resultant magnitude of 13 m13\text{ m}; 8 m8\text{ m} East and 6 m6\text{ m} West matches a resultant displacement of 2 m2\text{ m} East; and 9 m9\text{ m} North and 12 m12\text{ m} East matches a resultant magnitude of 15 m15\text{ m}.
Each vector combination is resolved according to its directional alignment: perpendicular displacements require the Pythagorean theorem (R=A2+B2R = \sqrt{A^2 + B^2}), whereas anti-parallel collinear displacements require vector subtraction.

Step-by-Step Solution

1
Identify orthogonal vector scenarios
Perpendicular displacement vectors form right-angled triangles.
Directions such as East-North, East-South, and North-East are at 9090^\circ relative to one another.
2
Calculate magnitudes for orthogonal pairs using the Pythagorean theorem
For 3 m3\text{ m} and 4 m4\text{ m}: 32+42=5 m\sqrt{3^2 + 4^2} = 5\text{ m}. For 5 m5\text{ m} and 12 m12\text{ m}: 52+122=13 m\sqrt{5^2 + 12^2} = 13\text{ m}. For 9 m9\text{ m} and 12 m12\text{ m}: 92+122=15 m\sqrt{9^2 + 12^2} = 15\text{ m}.
The magnitude of two perpendicular vectors A\vec{A} and B\vec{B} is given by R=A2+B2R = \sqrt{A^2 + B^2}.
3
Calculate net displacement for opposite collinear vectors
For 8 m8\text{ m} East and 6 m6\text{ m} West: 86=2 m8 - 6 = 2\text{ m} East.
Vectors pointing in opposite directions along the same axis subtract algebraically, retaining the direction of the vector with the greater magnitude.

Key Concept

Addition of Perpendicular and Collinear Displacement Vectors
Estimated Time:1m 30s
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