Engineering Mechanics — Concurrent forces:\nWhich of the following best describes concurrent forces in statics, i.e., forces acting on a body whose lines of action share a common geometric condition?

Introduction / Context:
In engineering mechanics and statics, force systems are classified by the geometry of their lines of action. Understanding what makes forces concurrent is fundamental for applying equilibrium conditions and simplifying complex systems into resultants acting through specific points.

Given Data / Assumptions:

• We are dealing with ideal, rigid-body statics.
• “Concurrent” refers to the geometry of lines of action only, not magnitudes.
• Options contrast collinear, coplanar, and point-intersecting arrangements.

Concept / Approach:
Forces are concurrent when their lines of action intersect at a single common point, irrespective of the angle between them or whether the forces are coplanar or spatial. This permits replacing the system by a single resultant through that intersection when appropriate.

Step-by-Step Solution:
Identify the definition: “Concurrent” means meeting at a point.Collinear forces lie on the same straight line (a special case of concurrency but overly restrictive).Coplanar forces lie in the same plane; they may or may not meet at a single point.Therefore, the precise descriptor is “meet at one point.”

Verification / Alternative check:
A common test is to draw multiple non-parallel lines. If you can pass them through a single point, the system is concurrent; if they merely share a plane, they are coplanar; if they share a line, they are collinear (which is a subset, not the general definition).

Why Other Options Are Wrong:

• lie on the same line: Too restrictive; that is collinearity, not general concurrency.
• meet on the same plane: Coplanarity does not guarantee intersection at one point.
• none of these: Incorrect because “meet at one point” is correct.

Common Pitfalls:

• Confusing coplanar with concurrent.
• Assuming parallel forces can be concurrent; strictly, parallel distinct lines never meet, so they are non-concurrent unless collinear.

Final Answer:
meet at one point