Classification of force systems — which term fits? Forces that are concurrent (meet at one point) and whose lines of action also lie in the same plane are called:

Introduction / Context:
Correctly classifying force systems helps you choose the right equilibrium equations. For particles (or pins) with forces meeting at a point, ΣF = 0 in two orthogonal directions is sufficient in 2D; for general rigid bodies, you must also consider moments.

Given Data / Assumptions:

• The forces meet at a single point (concurrent).
• Their lines of action lie in the same geometric plane (coplanar).
• We are naming the type of system only.

Concept / Approach:
Terminology: “coplanar” refers to lying in the same plane; “non-coplanar” means 3D distribution. “Concurrent” means all lines of action intersect at a common point; “non-concurrent” means they do not. Thus, a set of forces meeting at one point in a single plane is a system of coplanar concurrent forces.

Step-by-Step Solution:
Identify planarity: all in one plane ⇒ coplanar.Identify concurrency: meet at one point ⇒ concurrent.Combine descriptors ⇒ coplanar concurrent forces.Select the option that states this explicitly.

Verification / Alternative check:
Particle equilibrium is a classic example: weight, normal reaction, tension at a point are coplanar and concurrent; ΣF_x = 0 and ΣF_y = 0 ensure equilibrium without needing a moment equation about that point.

Why Other Options Are Wrong:

• Coplanar non-concurrent: lines of action do not meet—different class.
• Non-coplanar concurrent / non-concurrent: imply 3D, not the 2D case described.

Common Pitfalls:

• Confusing “passing near a point” with true concurrency; the lines must intersect at exactly one point.

Final Answer:
coplaner concurrent forces