Resultant force magnitude via vector addition

Steps:

• Identify the two forces: 3 N and 4 N acting at right angles.
• Confirm the angle between them is 90 degrees from the diagram.
• Apply Pythagoras' theorem for perpendicular vectors: resultant R = √(3² + 4²) = √(9 + 16) = √25 = 5 N.
• Verify no other components affect the magnitude.

Why C is correct:

• The magnitude of the resultant of two perpendicular forces follows the Pythagorean theorem in vector addition, yielding exactly 5.0 N.

Why the others are wrong:

• A: 1.0 N is the difference |4 N - 3 N|, incorrect for addition.
• B: 3.5 N is the average, not a vector operation.
• D: 7.0 N is the arithmetic sum, ignoring the angle.

Final answer: C