Resultant of perpendicular forces: 6 N and 8 N at right angles Two forces of 6 N and 8 N act at right angles to each other. What is the magnitude of their resultant?

Difficulty: Easy

Correct Answer: 10 N

Explanation:


Introduction / Context:
Combining non-collinear forces requires vector addition. When forces are perpendicular, the Pythagorean theorem directly gives the resultant magnitude. This appears frequently in statics and dynamics when resolving orthogonal components.


Given Data / Assumptions:

  • Magnitudes: F1 = 6 N, F2 = 8 N.
  • Right-angle between vectors.
  • Planar force system.


Concept / Approach:

For perpendicular vectors A and B, |A + B| = √(A² + B²). This arises from the dot product with zero cross term since cos 90° = 0.


Step-by-Step Solution:

Compute squares: 6² = 36, 8² = 64.Sum: 36 + 64 = 100.Square root: √100 = 10.


Verification / Alternative check:

Construct a 6-8-10 right triangle (a scaled 3-4-5 triangle), confirming the resultant magnitude is 10 N.


Why Other Options Are Wrong:

5 N and 7 N are too small; 12 N equals the arithmetic sum, not the vector sum; 8 N equals one component only.


Common Pitfalls:

Adding magnitudes arithmetically; forgetting that perpendicular components combine quadratically.


Final Answer:

10 N

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