Vector Addition of Forces

Steps:

• Identify the 4N and 3N forces as vectors with magnitude and direction.
• Add vectors using the head-to-tail method: place tail of 3N at head of 4N.
• Draw resultant from tail of first vector to head of second.
• Verify magnitude via Pythagoras if perpendicular, or law of cosines if angled.

Why A is correct:

• Diagram A applies the parallelogram law, where the resultant is the diagonal of the parallelogram formed by the two force vectors.

Why the others are wrong:

• B shows scalar addition, ignoring direction.
• C incorrectly places vectors tail-to-tail without forming a resultant.
• D depicts subtraction, reversing one vector's direction.

Final answer: A